IMG/Attachments don't seem to work

[dTune]

I don't seem to be seeing the [IMG] code pictures or attachments.

Some IMG's show up, but for example the "Show us your basses thread" had mostly posts like:

Here's mine.
(I think this is were the image should've been)
Ain't she a beauty?

Weird.. And i have the show images -option on.

Also, every time I try to check out at an attachment i get the message:

Invalid Attachment specified. If you followed a valid link, please notify the webmaster

I think this might be because the pics are deleted, but then again it would mean almost all the pictures are deleted, because I haven't found a single one.. But the attached thumbnails work

I also checked if this is due firewall settings, but I don't see them even with the firewall off.
Might be the browser settings, I don't understand most of the IE options available.

Couldn't find anyone having the same problem before, so any ideas?

[embellisher]

We had a software upgrade back in January. Any file that was attached before the software upgrade was lost. All of those dead links are from before the upgrade.