Funkydunk,
That was one of the first things I changed when I began getting the errors and it fixed the problem until my file limits were reached (which was a totally different problem that resulted in templates_c errors). After cleaning out over 5000 un-needed files from my server, the new errors are gone. I believe it is now default (as of version 3.4.
with the $use_sub_dirs = false.
From what I understand, with the sub directories turned on, there is a conflict with the PHP safe mode setting. For older xcart versions running with PHP safe_mode ON, it is probably essential to turn off sub directories. With safe_mode OFF, sub directories seem to be OK.
Another problem I had with safe_mode was that it was OFF for my main server space, but my security certificate (HTTPS) was on a different server with safe_mode truned ON. Everything worked fine for the customer until they entered the secure server. My ISP refused to disable safe_mode for that server. Needless to say, I'm now with a different provider.
Hope this helps anyone else who runs into the same issues.
Piper