Are you in safe mode with networking? (F8 at startup)
Don`t use system restore.
Download malwarebytes and do a quick scan, remove selected when it finishes, then do a full scan.
It sounds like you do have some malware, download malwarebytes and do a quick scan followed by a full scan.
If the virus still won`t let you download even in safe mode, use the following method.
Download malwarebytes using another computer to memory stick/external/ disc.
After you you click to download, click save instead of run, when box opens up click computer and then click the drive you want it to be saved to.
Before saving it rename the mbam-setup.exe to userinit.exe
Remove the disc/memory card, place in your infected computer, then run the set up.
Start up in safe mode (F8) to run the setup.
Do the quick scan first, followed by the full scan.
Turn off system restore before you scan if the virus hasn`t already disabled it.
Don`t forget to turn it back on.
The reason for renaming the file, I believe, is so that the malware doesn`t recognise it as antimalware.