|I think he means to try to use System Restore to return the system to before the infection go in.|
You cannot just roll it back an hour, but you can restore it to any restore point that is stored on your computer. Windows automatically creates a restore point once a week and anytime a program or update is installed.
First try running a full scan with Malwarebytes, and then a full antivirus scan with your antivirus software after updating it, BUT as above, try both of these in Safe Mode (tap F8 repeatedly at boot up and select Safe Mode with Networking from the list (use arrow keys) and hit enter.
If for any reason neither one can be launched (or installed and launched), then click on start, Search, and type System Restore and search (or I believe you can get to it in XP by right clicking on My Computer, selecting Properties, and the restore tab) and run System Restore. You should choose a restore point significantly before the infection was identified since it may have been laying low for a while, click on 'show more restore points' if needed. When you select an older restore point, you will not loose any files you have saved, just installed programs and updates so going back an extra week is not a problem. After the update completes and restarts, scan with both as above in normal mode before you can consider yourself clean of the infection.
You have to be a little bit crazy to keep you from going insane.