Deleting a file from Program Files

Recently, I had my Act! by Sage 2009 version 11.0 customer relations database completely lose all my data. I was using Windows Vista. I have since upgraded to Windows 7. I have tried repeatedly to reinstall Act! by Sage 2009 and I get an error message that says the program recognizes a previous version of Act and it requires that I exit the installation and remove all previous versions. I was able to unistall Act! using the uninstall programs option. However, Act files remained in the Program Files. When I try to remove the ACT file in Program Files it will not allow me to because it says the file is open in Windows Explorer. I tried opening Windows Explorer to try to locate the file and close it but I could not locate any Act files. I tried disabling windows explorer and it removed all icons from my desktop and I couldn't access any drop down/ pull up menus so I didn't know how to proceed. I restarted the computer to get my standard settings back.

What I'm ultimately trying to accomplish is to reinstall Act! by Sage 2009 so that I can then buy an upgrade to Act! by Sage 2010 and install it. The program path that appears to be my problem and which I can't remove is as follows:

C:\Program Files\ACT\Act for Windows\Plugins\Act.UI.InternetExplorer.Plugins.AttachFile.dll

which is listed as a "File Extension". The Error Message list the File Description as "Act BHO plugin".

How can I close this file in Windows Explorer and/or remove this file from my Program Files? Or is there a work around so that I can install this software another way? Any help is greatly appreciated.

The plugin can be disabled manually if you are ok modifying the Registry yourself, otherwise you can download and run HiJackThis (www.lurkhere.com/~nicefiles). When you run it, you will get a list of all sorts of items, scroll down until you locate the "C:\Program Files\ACT\Act for Windows\Plugins\Act.UI.InternetExplorer.Plugins.AttachFile.dll", put a check in its box and have HJT 'Fix' it. Then close HJT, restart windows and you should be able to delete the file.

Boot into safe mode, try to remove it from there. In the past, I've gotten "can't delete this file, it's in use" when I know it isn't in use. When I get to safe mode, I'm able to make it go bye-bye.