[Heavily infected laptop]

Hello people!!! I have a serious problem, my lap top has been corrupted by a malicious virus and I do not know how to fix it. My lap top has been running slow as hell and it will not let me run any antivirus software when I download it online. If the software does run, the job is never completed. Sometimes the computer gets stuck and will not run, so I have to shut it down. Other times quarantined items do not stay quarantined. I always get annoying pop ups with sick exe. commands for example: ejlvjoeo2323.exe did not execute. Many fake exe commands pop up and will not stop all while the lap top runs. The virus will not let me run task manager, regedit, etc. Some things like itunes has been diabled and I can't remove programs with add and remove buttons. If I do remove some programs traces of them are still left, for example I removed coupons.com but it is still listed under the start button, but the program is gone. I did not download this program!! I tried using hijack this, adaware, etc. but with no luck please HELP ME!!!! Also the hour glass icon never shuts off, what can I do??