Mac OSX has a safe mode function where you hold down the shift key during boot -- I did that and ubuntu 9.01 appeared to boot into Safe mode. Firefox Froze like a rock.

I have a theory that because Firefox can use a lot of memory, it can be the first indication of hardware problems as it is probably working the pc harder than other apps.

Was the upgrade the only thing you did to the pc?

Thanks for the response. I had Ubuntu 8.04 working well and then I got a book with a dvd that included 8.10 and I did the upgrade. I don't know if firefox was still working, but the next time I powered up, it offered to upgrade to 9.04 and I allowed it to proceed. After that Firefox intermittently freezes the system.
When it works, it seems to browse just as it should, but when it fails it locks the system hard. SSH connection Fails, Keyboard lights won't change state, mouse has no effect and ctrl alt backsp has no effect.

I will run the diagnostics available on the Live CD.

Thank you for taking the time to help me with this.

Running at around 30 passes of memtest86+ on 477 mb memory Don't see any errors

Hmmm, this sort of thing is a pain. I think you have to keep adjusting things to see if it makes a difference, e.g. turn down graphics . Unless anyone has any other ideas.

I am on Ubuntu 9.04 - kernel 2.6.28-15-generic and the Firefox about states it is:
Mozilla/5.0 (X11; U; Linux x86_64; en-GB; rv:1.9.0.14) Gecko/2009090217 Ubuntu/9.04 (jaunty) Firefox/3.0.14

I did have a similar freeze problem, but it turned out to be a cheap SATA lead, and now no problems.

Use the Synaptic Package Manager to uninstall (search for firefox). Right clcick on each entry and select to completely remove. After removing, install sun-java6-bin, then Firefox (3.5.5pre works for me and is in the repositories).

Didn't work - Marked sun.java6.bin and installed that
Then
Marked all items named Firefox 3.5 and installed that.
Did an Upgrade that was available
Executed firefox 3.5 and it froze immediatly because it came up fullscreen
Firefox 3.0 was coming up ppartial screen and the failure would occcur when the pointer moved to the middle of the firefox screen.

I am not quite sure what its the problem, my other guest they don't have the problem like I do. they use Windows, and I use Linux.

I am losing network bandwidth and I am quite frankly I am not sure why, I don't have allot memory 495.6Mib But I clean my PC every few days with "BleachBit"
Date.......CPU..........Network Receiving...........Sending
Oct/08.....12%.........313.5Mib.........................10.5Mib
Oct/12......47%.........0.0 Mib...........................0.0 Mib ..... ( I have Internet)

I have read some where on the magazine Network receiving suppose to be higher.
so how can I fix this issue? please i am having allot problems, I u use cable from Comcast

I am not quite sure what Information you might need from me to give.
Thank you very much
Note:
I use Ubuntu 8.04 LTS

Done Deal! System came up and asked me if I wanted to upgrade to 9.10 and I said Sure.
The upgrade occurred and seemed to fix firefox.
Its a wonderous thibg :-)

Myabe the issue is not Firefox, but rather your java install. Be sure to use the Synaptic package manager and install the sun-java6-bin.

I did the java6 install earlier and it did not resolve the issue
I also installed the Firefox 3.5 stuff but furefox still froze the system.
The upgrade to 9.10 seems to have resolved the issue. Firefox shows at 3.5 now and java6 shows as installed in synaptic and I am no longer seeing the system freeze up.