How max user's can be in one project?

[yduma]

How max user's can be in one project?
I am using Mantis 1.1.2.
I have some project's with more than 300 user's and when I want to delete one, or add some category, I see next -


APPLICATION ERROR #2800

Invalid form security token. Did you submit the form twice by accident?
Please use the "Back" button in your web browser to return to the previous page. There you can correct whatever problems were identified in this error or select another action. You can also click an option from the menu bar to go directly to a new section.

and I don't see button - Delete All in user list.

In another project with 10-20 user's - everything good.

Thanks!