Microsoft Visual C++ Runtime Library

Hello all. I have an Acer desktop running Vista Home Premium and it's been giving me some grief lately, and I was hoping to get some help. Every time i open up my video folder I get this error message (or one similar):

Microsoft Visual C++ Runtime Library
Runtime Error!
Program: C:\Windows\explorer.exe
This application requested the Runtime to terminate it in an unusal way.
Please contatc the application's suppor team for more information.

I can see that it's trying to load a preview of some of the files (a couple of 3GPs from my phone), but that error comes up before it does. After I click OK Windows Explorer crashes and restarts. This is the info from Event Viewer:

Log Name: Application
Source: Application Error
Date: 5/05/2008 5:23:19 PM
Event ID: 1000
Task Category: (100)
Level: Error
Keywords: Classic
User: N/A
Computer: ACER-DESKTOP
Description:
Faulting application explorer.exe, version 6.0.6001.18000, time stamp 0x47918e5d, faulting module ShowErrMsg.dll, version 2.5.23.4035, time stamp 0x462f11b3, exception code 0x40000015, fault offset 0x0000860c, process id 0xf8c, application start time 0x01c8ae7fb285a46f.

I also get a Runtime error with Internet Eplorer when I click on icon in Windows Live Messenger to check my emails. This is from Event viewer:

Log Name: Application
Source: Application Error
Date: 5/05/2008 5:59:43 PM
Event ID: 1000
Task Category: (100)
Level: Error
Keywords: Classic
User: N/A
Computer: ACER-DESKTOP
Description:
Faulting application iexplore.exe, version 7.0.6001.18000, time stamp 0x47918f11, faulting module mshtml.dll, version 7.0.6001.18023, time stamp 0x47be570a, exception code 0xc0000005, fault offset 0x0015c0f7, process id 0x16f4, application start time 0x01c8ae85ec10927f.

So can anyone offer any suggestions? Any help greatly appreciated.