The common plugins are Adblock Plus and Download Status Bar? You wanna try removing them?

Seeing as the line was there in Safe-Mode which has NO add-ons running, I think it's safe to say that those aren't the problem. But I'll try disabling them anyway. Nope, no difference.

The two things I see are that this ONLY happens with Mandriva Linux from what I've seen online so far and it ONLY happens with Firefox 3 (i.e. Firefox 2 looks fine). So it just seems like a chicken/egg scenario.
Something IN Mandriva isn't liked by Firefox3.

The other thing is it only corrupts *INPUT* box fonts while typing and moving the mouse makes it go away temporarily. It moves while you type too. OUTPUT or rendered screen text always looks perfectly normal.

I finally managed to get fluxbox to run from init 3 (still won't run from KDM for some reason) using 'init /usr/bin/startfluxbox' and the problem appears there too so it's not KDE 3.5 or 4.0 window managers causing the glitch.

hmm, seems like a conflict between mandriva and firefox alright. Have you reported this as a bug on mandrivas support pages and / or mozilla? After all, it is a beta version you are running?

This is a problem with Mandriva's default theme, Ia Ora. Upon installing QtCurve for both Qt3 and GTK2 and switching to it using the KDE Control Center (under "style"), the blue lines no longer show up.

I tried switching themes to Keramik and I still get the same lines in Firefox. I'm using KDE 3.5, so the QtCurve theme won't matter (KDE4 from what I can see).

Edit:

I just installed Mandriva 2009 as an update and after correcting where it screwed up the Grub entry (and thus made my system unbootable except by recovery), whatever was changed in 2009 seems to have corrected the line issue thus far. It also apparently modified all my Compiz settings, etc. and reinstated services I got rid of like Kerry Beagle. So who knows what all has changed, but at least I don't get those horrible lines anymore.

Edit2:

Now I've got a new problem with Mandriva 2009.0. My 2nd monitor is a 24" flat-screen LCD and my primary monitor is a 19" CRT. Whereas before the 2nd monitor showed whatever resolution I wanted just fine and KDE 3.5 adapted just fine, now the "KDE Desktop" will only show up as 1024x768 (what I have the CRT set to) regardless of what resolution the 2nd monitor is set to. In other words, if I set the LCD to 1900x1200, I'll get this "little desktop" inside the display like a minaturized version inside a larger black abyss. It doesn't scale the desktop up to fit the display (the mouse can move anywhere, though but the windows will only move within that small area). The only way I can get KDE to fill the screen is to select 1024x768 for the LCD, which isn't exactly optimal for a widescreen 24" monitor. It worked perfectly fine before with any setting when I was using Mandriva 2008.1. The update seemed to screw something up. I've restored my X11.conf file to what it was before; it doesn't matter. It does the same thing. I've reset nvidia-settings and tried different modes and nothing matters.

It's also obvious that Mandriva 2009 is using a different window decoration than it was before I upgraded. Kcontrol still says it's set to "la ora" for the window decoration but it's clearly NOT. It has some light blue transparent decoration with large white letters and a big honky "X" for the close button (much thinner looking for the 'real' la ora). Whatever this theme is, it's not present in the KDE Control Panel and trying to change the decoration there does not work. If another manager is running (Emerald?), I'm unaware of it. (Ok it appears to be the GTK decorator running the "Cairo" theme).

I also noticed the Mandriva 2009 update did not install KDE 4 even though that's supposed to be the default for it. I have a feeling these massive style "updates" still don't work right.

It'd be nice if I could get my 2nd monitor working right again. Fluxbox still won't run either from the KDM login panel. It hasn't worked ever since I installed Mandriva 2008.0. The only way I can get it to work at all is to force it on by going to init 3 and then using 'xinit /usr/bin/fluxbox' Otherwise, it doesn't work. I used to enjoy Fluxbox with a green Matrix theme and a few dock apps, but no more I guess.

I finally found out why Fluxbox wouldn't work with Mandriva 2008 and 2009. If you have it set to use Compiz 3D effects in the Mandriva "Configure Your Computer" panel (under desktop effects), then Mandriva enables Compiz as soon as you click login (i.e. before the selected window manager or desktop starts). Thus, the Compiz window manager was already running when Fluxbox attempted to start and thus it refused to start since another window manager was already running.

If you set Mandriva to NOT use desktop effects then Fluxbox and IceWM, etc. will all work fine again. I assume if I want to have compiz running ONLY for KDE and/or Gnome, I'd have to do some manual editing for those entries or something and bypass Mandriva's control panel setting. It also explains what happened to the La Ora window manager in Mandriva 2009 (when it starts Compiz first, it uses its window manager instead with KDE or Gnome).

Meanwhile, Fluxbox works best using two separate displays but KDE 4 works best with Twinview. In Mandriva 2009, I can't get a proper 2nd display with KDE 3 when using the desktop 3D Compiz effects, but now that it's turned off, it will display correctly (go figure). I don't see any easy way to auto-switch the two types of displays by desktop method. And if I set up a 2nd start bar, etc. for the 2nd monitor in Twinview, it ends up in the main display if I switch to separate display mode. It'd be nice if that whole setting/xorg thing could be integrated right into something like KDM and have each entry switch automatically. I have the feeling this is possible but would require some scripting.

I just tried "compiz --replace" in KDE 3.5 and it did come up and left the "La Ora" window decorations in place, but my 2nd display immediately went back to the improper display problem whereas the desktop fills up 1024x768 of real estate on the screen even though the overall size is 1280x720 (thus leading to a desktop that doesn't fill up the whole screen). This must be a bug in the newer version of Compiz or something since the version in 2008.1 didn't have this problem.