Check your HKCR\software\Adobe\Acrobat\Exe key. The (Default) string value setting of the path to your application must be in double quotes. (ex. ""C:\Program Files\Adobe\Reader 8.0\Reader\Acrord32.exe"") If it does not you need to right click it and click Modify. Add single quotes to the path. this will make it double quoted in the previous. I have seen several installtions set the key w/o the quotes.