AGP Failure?

Hi,

Soltek SL-75FRV
Athlon XP2000
GeForce Ti-4200
2xHDD
1xDVD+/-RW

My box has been switched on permanently for nearly four months. I've been
away on holiday for a week and decided to power off.

On my return I turned the box on but there was no signal to the monitor. The
disks were spinning but I couldn't see anything. I wiggled a few cables etc
before deciding to fit an old Riva TNT2 AGP card. This worked fine.

Ahah! The 4200 must be knackered - great excuse to buy a 6600GT. No joy -
the GT at least allowed me a glimpse of the Soltek BIOS splash screen then
it froze.

I tried a GeForce 5200 with the same result. In fact the 4200, 5200 and 6600
all exhibited the same symptoms: at some point between power up and logon
the screen would either freeze, be garbled or not send a signal to the
monitor.

At this point I replaced the power supply (350W).

Still no joy - only the Riva TNT2 card works which is as solid as rock.

I've run out of ideas. Any suggestions?

Martin