It sounds like your dns or host file is damaged. Download and run this program and it should get you going. Winsockxpfix
This will rest your dns, host file, renew your ip address. After this repair the best thing to do would be scan your system for spyware since your problem is one of the things spyware can do. IThis should work for you, please rate my solution if it does.
Over 21 years supporting/repairing PCs and printers