We have McAffee on there and had done a scan with no viruses or anything.

The install was a clean install.

Components:
MSI P6N SLI Platinum LGA 775 NVIDIA nForce 650i SLI ATX Intel Motherboard

G.SKILL 4x1GB 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory

SAMSUNG SpinPoint T Series HD501LJ 500GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive

SAMSUNG Black 18X DVD+R 8X DVD+RW 8X DVD+R DL 18X DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 48X CD-R 32X CD-RW 48X CD-ROM 2M Cache E-IDE/ATAPI DVD Burner

EVGA 256-P2-N541-T2 GeForce 7600GS 256MB 128-bit GDDR2 PCI Express x16 SLI Supported Video Card

Intel Core 2 Duo E6420 Conroe 2.13GHz 4M shared L2 Cache LGA 775 65W Dual-Core Processor

We have gotten different versions of the same error message:

Explorer.exe instruction of 0x72bba0fd referenced memory at 0x72bba0fd required data was not placed into memory because of an I/O error status of 0xc0000185. Failure-security options

and the same message with different numbers:

0x76da70 I/O error status of 0xc0000185


Thanks for the responses