Problem with 3.7 - is the zip file ok?

The website had 3.3 running and I attempted to update to 3.7; unsuccessfully.

First the zip file unpacked wrongly in CPanel, failing to yield all the files. A new copy appeared to unpack correctly on my local machine (right size, same list of files as in 3.3), but the uploaded files still generated the same errors.

I deleted 3.7 and uploaded 3.6 and everything worked fine.

I then downloaded fresh copies of 3.7 and tried again, but had the same problems - the module file cut off at line 1031 in the middle of a comment, and then a function failed to find the right things and threw an error that prevented the page from loading at all. Was it progress to get 2 errors instead of one? I cleared Drupal's caches between each attempt (insofar as the Admin menu command clears them).

I can't tell what I did wrong, and log this just in case there is a problem with the zip file. Sticking with 3.6 for now.