Problem with XFree86 and Compaq's Presario Radeon M7

[Nutria]

Hi.
I don't know is here is the correct place to ask something like this. Compaq don't gives me support with some problem that happens in Linux, because it's not the OS installed in factory, and I also have not found any compaq+linux forums where ask.
The problem is that my Xwindows don't work properly, X run but some vertical lines (1 each 4 or 5) are shifted or something like that.
One developer of XFree86 have told me that the PCID is from Compaq, not from ATI, so probably my card is modified by Compaq, so the radeon driver don't work with this modification.
I've tried SuSE 7.1, 8.0, Redhat 7.1, 7.2, KNoppix. All with XFree86 4.2.0 and latest drivers for radeon have same results.
Someone more seem to be same problem than me, but solution proposed by other don't seem work.
The computer is a Compaq Presario 2812.

My e-mail for any question, xfree log, etc. is nutria2k2@terra.es

Thanks.