When you checked for viruses, did you do it in Safe Mode? Note that some viruses can hide themselves from your antivirus program in normal mode, so you really need to scan in Safe Mode. To get into Safe Mode when you first power up, hit F8 about once a second until you get the menu and select Safe Mode.
You can check for corrupted system files. Open an administrator command prompt and run SFC if the above doesn't help. Click START, then type CMD in the search box, right-click CMD.EXE and click Run as administrator. Then from the command prompt type sfc /scannow.
I hope this helps. Good luck.
Recently I have encountered a strange problem with computers at my house. They have started performing really slowly.
Most of the time, the boot time took extremely long time, any action would eventually ended up in "Not responding" and crashing the explorer.exe.
I've already tried to run several virus/spyware scans to no avail - (Comodo Internet Security).
I've tried to update all of my drivers - didn't fix (the newest driver for NIC for 1st PC completely disabled the NIC afterwards and rendered it unusable.)
I even tried to do a complete OS reinstall - this seemed to fix the problem for a short time. Then the slow performance occurred again.
This problem occurs with both of my PCs:
OS: Windows 7 64-bit
CPU: i5-750 2.66 GHz
GPU: ATI Radeon HD 5860
RAM: 4 GB
2nd LAPTOP (fairly old one)
OS: Windows XP 32-bit
CPU: Intel Centrino Duo T2500
GPU: ATI Mobility Radeon X1600
RAM: 2 GB
Any help will be appreciated. Thanks in advance.