Hello and thanks again for your suggestions…BUT, first I have to say I must reported the error message incorrectly. It is saying that Avast can’t find the file specified:

Splash cannot execute the following program:
c:\Program Files\Alwil Software\Avast4[b]ashEnhcd.exe[/b]

First I checked to see that I have the ashEnhcd.exe file, and it is there, (as well as the ashSimple.exe file). I tried your suggestion of repairing Avast! I went to Settings, Control Panel, then Add/Remove Programs. When I double click on avast! anti-virus, It takes me to Avast anti-virus set-up. The options I have (no scrollbars to be found), are Change, Uninstall, or Update. I have tried both Change and Update. It says I am up to date. I still am having the same problem: unless I disable SpySweeper, I cannot start avast! at all by right clicking on the systray icon (blue ball with a in it). If I go to the Start menu, Programs, Avast anti-virus, Avast anti-virus, I get the Avast Professional screen where it scans your memory, then a pop-up box with the above mentioned error message:

Splash cannot execute the following program:
c:\Program Files\Alwil Software\Avast4\ashEnhcd.exe

The only option is to click “ok” in the box which terminates the Avast start-up screen. If I shutdown SpySweeper, I can start up the Avast! Enhanced UI either by right clicking the systray Avast! icon or through the Start menu.

Any other suggestions are much appreciated. This only started happening the last time Avast! updated yesterday.