I've been digging around a bit more and found that the SDT forums uses much more (little more than twice) CPU/RAM than the Ryonani forums despite having similar traffic patterns and a database half the size. I will be taking steps to optimize the SDT forums as well as the Ryonani forums as much as possible over the rest of the day to see if that helps with the errors.
I've already done most of what I can to the SDT forums short of upgrading to SMF 2.x.
You guys probably noticed the avatars are missing. I had to drop that table due to poor design in the existing forum software. I've reworked it to be more efficient but unfortunately the script to relink the avatars back to their owners simply doesn't work. However this fix does make a significant difference in efficiency. In case you didn't have your avatar saved anywhere but here, you can look for it in these piles: (and ideally for the sake of server load, setup your avatar to use the image from Imageshack instead of uploading it to SDT)
http://imageshack.us/g/847/avatar1ja.jpg/
http://imageshack.us/g/835/avatar1598.png/
I apologize for the inconvenience. If the errors are still popping up after tomorrow, then I will simply pay for a better hosting service.