I don`t know why
Probably because it didn't write the file itself, so had to build up its internal 'cache view' or whatever you call it for it, from scratch. That probably got corrupted somehow on the old install.
Maybe just drop this at CW tech support too, to go on the list of to-be-checked's for the next update.
Glad it's solved, but should not have happened - bundles are pretty useful, whatever some people may say about them.