Sometimes the BBC i-player refuses to offer a programme to download to the desktop i-player but will permit it to be downloaded to the Windows Media Player. The file format is .WMV, and although one I downloaded this morning can be right-clicked and played if you select WMP, it seems to be invisible in the WMP libraries so can't be accessed and played from WMP proper. At some point I saw a warning about corrupted library files. So far I've run the Microsoft online "fix-it" tool for WMP (no change), removed and then re-added and re-indexed the WMP Windows feature via the Control panel, and run "sfc /scannow" which is supposed to check and replace any corrupted hidden system files (nothing found.) The only change after all that is that it now runs the built-in example wmv file which it was earlier refusing to run. OK, there's a work-around but it's pretty aggravating that WMP12 (in Win7) can't seem to deal with files in a Microsoft-derived format! Has anyone else had this problem, and more importantly, found a proper solution?
Different OS, but likely of use to some: I use Media Player Classic, as installed with the K-lite Codec Pack. It means there's pretty much no audio or video file that I have any problems with, and I avoid the ridiculous bloat of Windows Media Player.