kapusta-
Whether or not you see them, there is no question in my mind that your computer is infected with adware, spyware and possibly viruses. Until you have it cleaned assume that anything you do on it can be seen by crooks and people looking to steal your information. This includes which sites you visit and the IDs and passwords you use. Furthermore, you may be inadvertently sending malware to others via email or files created on your PC.
I wish I could be more encouraging, but them’s the facts.