Windows Vista Open Excel doc & Windows Office 2000 Installer pops up

This problem is on my Gateway laptop, running Visa Home Premium (which has given me no problems) with 2 GB Ram on board.

The problem involves Office 2000 Professional installation media disk legally owned by me, an MS Office 2000 Pro disk, I have used successfully for years, in a desktop computer and now in the laptop that replaced the desktop. Never had any sort of problem till now.


THE PROBLEM:

Something weird is going on with my long-installed, long-used-without-a-hitch MS Office 2000 Professional Excel application. ONLY occuring in the MS Excel application! The other Office Suite applications "” Word, Access, PowerPoint, etc. work as they should.

Just today (on above date) whenever I try to open a previously saved Excel.xls file, whatever the file name, that I have opened frequently and successfully before, I get the Windows installer screen up, wanting to load my Windows Office 2000 Installer disk to install the Excel app.

This version of Excel has been successfully and properly and LEGALLY installed on my laptop computer for 2 years and has never acted up 'till today.

HERE'S THE WEIRD PART. The files, as I normally try to open them, are DESKTOP shortcuts to the Excel.xls files saved in a different folder. Now, whether I click on the Desktop shortcut OR the actual file itself, NO Excel.xls file will open; that action triggers the Windows installer function. BUT, if I go to Program Files\MS Office\Excel.exe and click on Excel.exe, the standard blank Excel.xls spreadsheet opens as it normally should.

AND if I create a desktop shortcut to Excel.exe, that opens any Excel.xls file normally AND within that blank .xls spreadsheet page opened by clicking Excel.exe, if I browse to ANY named and saved .xls file via File | Open file search, I can open in this blank Excel page window ANY of my named .xls files perfectly "” files I cannot open by clicking on them individually.

AND I can also drag 'n' drop any Excel.xls file shortcut onto the Excel.exe shortcut AND THE DARN THING OPEN SUCCESSFULLY.

Why named and saved .xls files or their shortcuts refuse to open on their own without going through the basic Excel.exe app is beyond me.

1. This behavior is recent, I opened my two most-used Spreadsheet files via their desktop shorcuts several times last week. Today, nothing will open in this standard fashion.

2. I even ran Windows restore point to last instance, dated 9/22/09, to no vail. The reason I ran this is that on the 22nd, last Saturday, there was a solitary program update installation "” an up date to a new version of Avast Anti-virus freeware version that let install on my computer.

[While I realize someone may simply advise me to let the Windows installer run, which I may have to wind up doing anyway, there must be something glitched up here and I have at present a concern simply running the Repair/Reinstall routiine will correct whatever is happening here.]

Anyone who can advise me as to what may be causing this weird behavior, any possible solution, registry hack, whatever, would be most appreciated.

Thanks all for your time and attention,

tvj