i have had a small problem with explorer lately (or at least that is what i think it is) it has happened a few times now, i start doing something, and the program stops responding, which i really dont mind that much, but the problem is that after i close the program, i cant do anything! i try to open files, and i cant, i try to use already running applications, and i cant, i cant even shut down or restart without physically pressing the button. its really starting to bug me, cuz i was trying to save an image, and it saved the filename, but it didnt have anything on it, so i lost the image. please help

My Computer
- Computer Manufacturer/Model Number
- Home Built
- OS
- Windows XP in 1, and Windows 7 in 2
- CPU
- AMD Athlon64 for both, 1.8GHz 2800 in 1, 2.2GHz 3200 in 2
- Motherboard
- MSI MS-6702 for 1, WinFast NF4UK8AA in 2
- Memory
- 768MB in 1, 1.5GB in 2
- Graphics Card(s)
- ATI D33053 in 1, Power Color HD2600 in 2
- Sound Card
- both onboard sound
- Monitor(s) Displays
- both ViewSonic, A70 in 1, E70f in2
- Screen Resolution
- 1280X960 on 2, and highest possiblke in Win 7 on 2
- Hard Drives
- Both 40GB, for now
- Cooling
- Both aircollerd systems
- Keyboard
- DELL QuietKey 1, Microsoft Wireless Laser Keyboard 5000 2
- Mouse
- Microsoft Wheel mouse optical USB 1, (same as above) 2
- Internet Speed
- 6Mbps