Solutions? Try Spybot, Malware, and if you don't have an antivirus, go with AVG its free.
Download all, and update all programs after downloading. Restart computer in Safe mode, and do a virus scan and spyware search with each program (one at a time). It may take a long time to scan, but let it do its job. Then see how it goes. Goodluck!!
^^ Yep..dont need to reformat. Its also good to DIY, so you're knowledgeable on how to fix these problems.
Boss, also try this. This will scan your computer performance. You can see where you're having problems with this also. http://www.pcpitstop.com/ Try the test n see how it goes.
baka naman may problem sa shells lang? Kase di ba pag nagright click niloload nya ang shells scripts ng files na highlighted? Try to download ShellExView.
After all's said and done, i think you'll end up with this suggestion. Unless you have very valuable data na di mo ma-backup and some setup with sentimental values
But go ahead and follow first all the other suggestions, malay mo one of them might help...at least for a while. That is if you have time to burn and enjoy late night troubleshooting.
Install a good antivirus and a firewall, when you fixed your problem.