Here's a puzzle:

All my files in my home directory somehow suddenly lost their w attribute, ie became ro. The execute and read bits were not affected, and the filesystem was still mounted rw. They looked like -rw-r--r-- I was not running X as root, never do. The user and group ownership were unchanged.

I was running KDE and first noticed it when I tried downloading a file and could only copy it to my Desktop, not my downloads in /home/me. I also had an open file in Kwrite which couldn't save. I had removed lesstif and added openMotif. Root's account seems to be the same, but I'm not sure the permissions weren't always that way.

I shutdown, ran fsck from init 1, looked at smartctl and there were no errors. Of course I couldn't run init 4 or startx from init 3, because no .Xauthority could be written, nor any .serverauthority.

So I typed chmod a+w *, and everything seems to be ok again.

BUT:

What could account for that, and what else might have been affected?

-rw-r--r-- means owner may read/write, group and others may only read. So I think they were in the correct state. This is the normal permissions on files in the home directory.

Perhaps, but I couldn't write to them. I see that I can no longer run Crossover either; is the ownership of /home/me supposed to be me and users or is it supposed to be root and root?

It should be me and users.

BUT - your case is not clear to me from your posts, the execute bit MUST be set on all those directories and sub directories. - That is, whereas files should be rwxr--r-- in the user home by default, sub directories should be rwxr-xr-x by default.

Hmm, so then the directory ownership got changed. Interesting, thanks.