Can you try to rename IL2 directory, to something like "IL21946_bad"? Then you should at least be able to install IL2:1946 again.
There is a program--freeware--that I downloaded that will probably help you. It is called Unlocker Assistant. Install it and run it. When you try to delete the file, you will get the same message that it is in use and can't be deleted--then Unlocker will kick in and you can unlock the file and delete it. A useful little gadget.
I found this helped me out when I had the same prob.
FB would not uninstall with the normal uninstall method, and after manually removing the probgram, it stubbornly refused to reinstall.
Resolution:
* remove the install folder manually
* remove HKEY_LOCAL_MACHINE\SOFTWARE\Ubi Soft\IL-2 Sturmovik Forgotten Battles
* empty "%temp%" from the Run menu
* empty "%systemroot%\temp" from the Run menu
* removed all shortcuts
It still would not reinstall.
Here is the tricky bit. Set folder display options to show hidden folders and files. In the Programs folder (XP), you will find a normally hidden "InstallShield Installation Information" folder. One of the subolders pertain to FB and is corrupt. To find out which - use Notepad and check the "Setup.ilg" files (do not save!!) for any text referring to FB. When you find the folder, NOTE THE NAME of the folder (in my case {8DF712DA-D325-4FD0-8DE8-E2D78FC3CDC3}, and delete the folder (or just move it somewhere else).
Then run Regedit and search it for the first part of the folder name - for example 8DF712DA. You will find two keys in the registered programs part of the registry that match this - makes sense. Delete these keys.
Set folder dsiplay options back to normal.
Cheers,
TT.
