Can't reply?!

[Sove92]

Try logging out and logging back in. I had the same thing happen once, and after doing so, it was fixed. That thread has incorrect information anyway; there is supposed to be a 15 minute delay between posts, but that is not true.

The forum software that checks for these daily limits is buggy.

Not very surpising, really. The forum sofware is vBulletin, developed by vBulletin Solutions, but the Dev Tracker, account management, post limits etc. are all coded by SE. A lot of their modifications are done to the core files which easily results in stability issues. It's almost a wonder the forum works as well as it does.