I have been getting the following errors at Windows log in.

MRT.EXE
The exception unknown software exception (0xc000409) occurred in the
application at location 0x77dd805d.

I also get an a svchost.exe error once in a while.

At shutdown I get a McShield.exe error (0xc000008), every once in a while.

None of the errors happen all the time, but the first two usually occur when
the computer is turned on the first time during the day.

The computer is a Dell Optiplex GX270, with Windows XP sp2, McAfee 8.1.

Any suggestions would be greatly appreciated