Installing Avast7 changed computer settings, made programs not work

I installed Avast Free Anti-Virus 7.0.1407 yesterday. I restarted my computer as it told me to, and found out that many of my computer settings were changed. My computer now shows a log-on screen (I’ve tried to change it back, but no luck). Notepad and Wordpad are working sporadically and the System Configuration Utility will not load at all (the error report says it’s the user32.dll file in the system32 folder - I did not change this file at all, and it’s only caused problems since Avast 7). I have to try to load my writing program (Liquid Story Binder XE) 15 or 20 times before it finally loads. My computer also seems to be running much more slowly than before. I tried a System Restore, but it didn’t help. Is there any way to switch back to the old version of Avast? Avast was working very well for me before this new version.

Have you tried uninstalling Avast and then checking whether the problems you mentioned still persists?

Avast can’t have made a login screen or changed things like Notepad, Uninstall, reboot and see how your machine behaves.

When you have done that,let us know how you got on.

To get further help you will need to give us details of your PC, Operating system and any other antimalware applications you have running.

As the last post. we need to know what operating system you are on.
May need windows cd rom for repair in recovery console to manipulate the computer to restore back to original config. Looks like windows file damage to me. windows system folder 32 user32.dll
Try and download malware bytes and update and do a full malware scan.

Well Avast has nothing to with the problems. Anyways you can repair the OS using its setup disk. It will restore the windows files.