What's wrong with me?
Almost every day I do 1-2 hours extra-time to finish some problem I stucked with. I can't just turn off my computer at the end of day like my colleagues do. It always seems like I doing nothing while trying to solve some problem without any result. So I feel guilty and try to do more. It exhausting me and I do even worse. And so on. Recursively. Any solutions?
Thanks in advance! =)

Yeah I agree with both the comments to some degree, there’s a fine line between self improvement and team communication / knowledge share. But on an emotional and mental level, If you don’t stop and take a break, you will burn yourself out on trying to solve the problem. Putting your own comfort, health and life first, tells yourself that you matter more than the job and it also makes you a better programmer. No one thrives in a hostile stressed environment, wether it is self appointed or not.

I have a similar problem. I almost never do that much overtime, but I do feel guilty if I haven't been able to make much progress in a single day. It makes me anxious, I'm always thinking of what I'm going to say on the next day's meeting (we have daily meetings). I don't think I'm being too slow, after all I only work 6 hours a day. I think I'm I'm kinda on par with my coworkers (speed wise), but still, it makes me anxious and I feel like I'm not doing enough.

It could be that their assignments are easier than yours...

The description of @CrazyJiM is a bit vague.

Don't be competitive about subjective facts.

Instead of trying to compare yourself to others, try being honest to yourself.

If you don't feel any process, maybe write a diary. I know some persons who constantly doubt everything as they have a very "inhuman" way of judging themselves. Inhuman meant that they try to work 8 hours straight on mundane tasks and wonder why they can't get a clear thought after 3-4 hours.

No shit sherlock, that's not how the human brain and psyche works.

Write a diary or make notes when you started working on what. Take breaks. When you hit a wall, pick another task to work on.

It's highly subjective what a person can achieve and what's the best way to get a job done.

Being competitive and judging yourself is a spirale downwards, as you just pressure yourself.

Reflect on yourself, yes. But let others do their job and you do yours.