Ok, but now I'm back to getting the MC error. I've done all fixes, reinstalls etc. suggested in the threads, got good copies of the zips (i assume - the sizes match what they should and they unzip as bf mod folder structure.) Got a copy of the BFBC.wmv file (it was there already).
Windows XP is correctly updated, recent hardware drivers, etc. BF2142 DLE runs fine and the launcher seems to quit ok after a while. I've tried increasing permissions for the fslauncher on the off-chance that the Vista problem is causing a similar effect in XP-SP3, but no luck.
One thing is left that make me think there is maybe more to the launcher process than just having the zip files - If I set the Version to 1000 in the fslauncher preferences, with the zips in the mods folder, I get the following dialog when I do an update:
[Sun Feb 22 17:33:09 2009] checking for new updates..
[Sun Feb 22 17:33:15 2009] new versions: ['1001', '1002', '1003', '1004', '1005']
[Sun Feb 22 17:33:15 2009] already have fsbuild_1001.zip, skipping download
[Sun Feb 22 17:33:15 2009] already have fsbuild_1002.zip, skipping download
[Sun Feb 22 17:33:15 2009] already have fsbuild_1003.zip, skipping download
[Sun Feb 22 17:33:15 2009] already have fsbuild_1004.zip, skipping download
[Sun Feb 22 17:33:15 2009] already have fsbuild_1005.zip, skipping download
[Sun Feb 22 17:33:15 2009] Error connecting to update server.
I always get that trailing connection error on the last line, no matter which zip files I have downloaded, or if I have downloaded none of them. This makes me suspect that there is meant to be a final initialisation file or command that I'm supposed to get, but dont.
And maybe that's also why the Version field of the fslauncher preferences doesn't update itself to 1005, even though it has detected that I have the files - I have to set it manually.
Anyway thanks again for all the help, I'll keep watch on the forums for any other fixes or updates and test them out as I see them.