2008 (late) MacBook Pro 15" Sleep Issue

Hey everyone,

I am experiencing an issue with my 2008 MBP where when instructed to sleep or the timer reached my MBP shuts down. Upon rebooting I receive an error message saying that the sleep timer has ran into an issue or something and I receive this error code: 0xd5f2a20d 00000031. Also, the fans seem to be running at higher than normal speed. I have reset the PMU and PRAM. (PMU by removing the battery and holding the power button and PRAM by Option-Control-P-R at reboot). This issue, including the high speed fan, has just started with todays use. I haven't had any issues out of the machine in a long time, except for a battery replacement in May 2019. Also, oddly enough the fan will only run at high speeds for a few minutes and will "calm down" after about three minutes at the high speed. If anyone could shed some light on this issue it would be much appreciated.