System Restore wont work

[trastevere]

Software repair Wizard System Restore keeps telling me your computer cannot be restored to ...(date) . NO changes have been made to your computer. I've tried numerous dates. Today I picked up a pop-up which repeatedly pops up and says Your computer is infected. ..It is very annoying.I have not clicked the white cross in red circle icon on the toolbar as requested as I suspect this is a rogue spyware. Norton 2006 scan has detected Adware.Spysheriff but can't get rid of it . Any help greatly appreciated

[trastevere]

Dear fender62, Thanks for your reply. Page was unavailable but I referred to a previous post and downloaded www.free.grisoft.com. This detected and got rid of 4 trojans. The red circle with white cross icon has disappeared from toolbar as has its irritating pop-up. For info, the items were all Trojan Horse Generic.2AVS - winstall.exe - pkbkqmqf.exe - cptuleeo.exe - pmhczqvf.exe I'm not now going to test System Restore in case it works and undoes all the good work done by grisoft AVG Thanks again