Opening Files Causes Computer to Freeze

Recently, our computer will freeze up if you try to access a file in explorer. Once it freezes, if you try to shut the computer down, you have to hard shut it down or it won't shut down at all. I have tried scanning for viruses and other malware, removing software, and running check and fix disk. The only time we really don't have issues is in Safe Mode. Not sure what the issue is, possibly a corrupt explorer.exe file, but I would have thought fixdisk would have rectified that. Expert advice would be appreciated.

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows XP Professional, Service Pack 3, 32 bit
Processor: AMD Phenom(tm) II X4 910 Processor, x86 Family 16 Model 4 Stepping 2
Processor Count: 4
RAM: 3583 Mb
Graphics Card: ATI Radeon HD 4350, 1 Mb
Hard Drives: C: Total - 939559 MB, Free - 876011 MB; D: Total - 238472 MB, Free - 94 MB; H: Total - 14307 MB, Free - 1987 MB;
Motherboard: PEGATRON CORPORATION, VIOLET3
Antivirus: Ad-Aware Antivirus, Updated: Yes, On-Demand Scanner: Enabled