It should be easy for your programmers to trim that "..." out of the title if people type it in, or they could just exclude the "." character all together from the title field.
It seems a little surprising that those characters have any effect on the vBulletin program. This program has been in use and tested like a Mack truck.
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Here's a sample from another vBulletin forum that I frequent where the titles have "..." in them without problems.