win32k.sys problem

My Optiplex GX280 frequently crashes after I type in my password and hit ENTER when turning it on. It then gives me this message: A problem has been detected and windows has been shut down to prevent damage to your computer. The problem seems to be caused by the following file: win32k.sys PAGE_Fault_IN_NONPAGED_AREA If this is the first time you’ve seen this Stop error screen, restart your computer. If this screen appears again, follow these steps: Check to make sure any new hardware or software is properly installed. If this is a new installation, ask your hardware or software manufacturer for any windows updates you might need. If problems continue, disable or remove any newly installed hardware or software. Disable BIOS memory options such as caching or shadowing. If you need to use safe Mode to remove or disable components, restart your computer, press F8 to select advances startup options, and then select safe mode. Technical information: *** Stop: 0x00000050 (0xE4E3E000, 0x00000000, 0xBF8730ED, 0x000000010 ***win32.sys – Address BF8730ED base at BF800000, DateStamp 45f013f6 Beginning dump of physical memory Physical memory dump complete Contact your system administrator or technical support group for further assistance. It does this about about one out every three times that I attempt to start it. It does not crash while I am using it. Any advice would be much appreciated. I see that there are many others who have had problems with win32k.sys.