Slow ladder walking

I'm walking very, very slowly, when trying to climb up/down a ladder, I just got a new PC,
it has no brand but it's costumized, here some details :

Windows 7
Nvidia Geforce 9800
Intel core I5

Does someknow how to set those properties, please, post it here.

By the way, I didn't get this kind of errors on my other pc, which is gone now.