XP Mystery NO SIGNAL on monitor

I've read a few forums reflecting the exact problem I am having. After installing a new EVGA Nvidia GF9500. Each morning I boot-up. Everything fine and I always check my E-mail and then go about my normal routines, leaving the computer to rest. After approx. 8 minuters, the monitor says "NO SIGNAL" and the tower indicates a constant hard drive as busy, the fans are running and NO MOUSE light. (USB Optical). System will not respond to any mouse/keyboard movement. The RESET button will not respond. I have to hold down the POWER button till unit goes off. Then restart. System boots up normally and everything OK for the day. This repeats each and every morning. EVGA help insists it's not the graphics card and suggests a problem with the power supply. (Antec430w) So I pulled a unused soundblaster card from the tower reducing load. Didn't solve situation. I've ran all kinds of scans, i.e. virus, malware, adware, etc. I've done error scans each time. Found nothing. EVENT viewer does not record anything related to this event. After all of this, I converted my mouse from USG to PS2 using the adaptor provided and that seems to have solved my problem. This problem did nnot happen with my older Nvidia card (GF8700). My question is "What in the world does the mouse in USB mode have to do with this shutdown of my system? "
Windows XP Pro SP3, Intel DC 2.4, MSI P6 MoBo, 4gig mem, GF9500 1 gig
400GB HDD (serial ata) Onboard audio.

 

Thanks for the replies... I have the very latest graphics drivers from Nvidia installed. I even went to EVGA and installed their lastest driver. Didn't fix a thing. As far as the PS, another forums post said he changed his PS to a 600W or so and that did not solve the problem. Bill1

 

Some points to check:

1. Is the fan on the card working ? Heat could be a problem.
2. Is there a power connector on the card ? Have you plugged in a power connector to that ?

 

Thanks supergeek... Fan(s) are running. Plugs are in TIGHTLY. I have removed, re-installed and reseated the graphics card and memory. I've checked all plugs for being tight and locked. Using the mouse as PS2 fixes the issue, but I would like to know why? Hardware or software? XP's registry?
Bill1

 

Addition: Are you overclocking your graphics card ?

 

When you plug in the mouse in USB, do you see any yellow exclamation mark in Device manager ?

If plugging the mouse in PS2 port solves it, there could be some conflict or driver problem with USB.

Are there any other devices attached to USB ?

 

I relpaced my older mouse thinking it was a problem. The new one is just like the old. Microsoft optical mouse. My graphics card has not been overclocked. Question. What about a later USB2.0 driver?

Bill1

 

Thanks RSINFO... I have a printer combo (fax/scan/print) plugged up....

 

Thanks..... I just installed the latest drivers from Lexmark.... I will converrt my mouse back to USB and tomorrow morn we will see what happens... Thanks Bill1

 

OK... This morn, system did NOT do its mystery shutdown.... However, the other day after I removed the Soundblaster, and the next morning, the unit did not shut down.... BUT I was not home for a while and when I returned, booted up and guess what? After about 8 or so minutes, it went down....
So today OK tomorrow we will see....

 

I think it's fixed............

This morning marks day number 3 that it has not done it's trick.... This is after I re-installed/upgraded my printer's driver. This must have been the problem....Like they say "all in due time ". Thanks good folks for all your help.... Bill1

 

MYSTERY partial shutdown...

My previous post on this subject indicated a sudden interuption on my PC about 10 or so minutes after initial boot-up. I.E. monitor no signal but case indicated HDD activity, fans working, etc. Will not reboot using the hard reboot button, but requiring a power down using the on/off button. Reboots back to normal and for the rest of the day, everything OK. WELL after some weeks of relief thanks to ur suggestions, ITS BACK. My mouse is PS2, same PS and the absence of a sound card plugged in. I have slightly overclocked my VGA Nvidia 9500 from default of 550 to a little over 600. Do you think that might be the problem? This is weird............