My daughters' Pc runs XP. In the past I have run Mepis and knoppix live cds on this Pc without problems and I am considering installing linux on this Pc permanently.

Yesterday I installed a Belin wireless card. This works fine under XP. However now I am having problems with the Mepis and knoppix live cds. In both when they get the stage of starting X there is a blank screen. Ctrl-Alt-backspace has no effect and neither does Alt-function key.
I can boot into knoppix if I specify run level 2 but if I then run startx it all goes blank.
Damn small linux worked fine. I suppose this is a problem with Xconfig/xorg.config but the live cd worked fine previously and I am suspicious because the only thing different about the Pc is the wireless card. Is this a known issue with wireless cards?