seriously strange problems

All - I've got some VERY VERY strange issues occuring with my 4.1.0 drupal install. Here's a summary of issues:

for user admin and my personal user account (belongs to admin role):

when posting events, after clicking "preview" or "submit"
causes the preview form and final submit event to have n/a
set as the content of the message - this occurs on Mozilla
1.3, IE 5.5 and IE 6.0 - so I don't think it's any strange
from submission issue

another user with "admin" privilages as his role has no
problems submitting events - I also promoted a test normal
user to have "admin" role privilages, and that user had
no problems posting events

I went back to edit/admin a Forum topic, basically delete
a bunch of Annotation entries that were erroneously tagged
for no apparent reason (about a dozen random entries,
no surrounding text matched any of the glossary items)

it continued to stuff the glossary entries back into the
text, even after I manually deleted the appropriate text
...and after I had turned off the "glossary" function

regular users with "authenticated user" role, which has
privilages of "post events", and "access events" are
not able to add events - they get directed to the "submit"
page, and "events" is not a content type they are allowed
to select

These are all adding up to weird stuff. I know it may be awfully hard to try decide where to provide help to look, but I would appreciate any thoughts from anyone. The site has gone live, and now I'm getting roasted because of a lot of these odd problems in Drupal. I really don't want to switch to another CMS because of this. I'm starting to get a bit comfortable with the code, so I can poke and prod some and see what I can come up with, if I get some good feedback.

Thanks in advance for anything!

v/r
Shane