Silent Hunter 3 wrong time of day

My dad has been having issues with Silent Hunter 3's game clock after he played 4 on the same computer (which i guess is known for having this problem).
What's happening is that the sun won't rise and set when it should, aka, it doesn't follow the computer's clock. I haven't been able to find anything on it, since I don't know really how to word it... but if anyone has the same problem with SH3, and fixed it, could you help? Thanks!

 

Well, he installed it on his new computer.
Also, he won't install anything else on that computer because he's always trying to keep things perfect. He also scans and cleans up all of his computers multiple times a day and also washes his hands before touching the keyboard even after scratching his head...
Also, my dad is an old computer guy that refuses to use any tools that aren't windows because he believes they will destroy his computer (then again, he still has his old computer built in 2000 and it runs better than it did before he bought it). Either way, I can't get him to install another game on that system, let alone a registry cleaner .
He bought a computer to use and run Silent Hunter ONLY... hahaha.
Anyway, all he has on the computer is Silent Hunter, no internet, and no programs that didn't already come with windows XP. The only installation he ever made was for Silent Hunter.

 

Well, he installed 3 first and it worked fine for some months, then installed 4 which is known for having the problem and it gave 3 the disease, sort to speak. Well, I doubt my dad will go through a re-install. It would literally take him a week to complete it including the time it takes him to 'prepare' his computer . I'll just go check it out the next time I go visit. Thanks for your help!