Upgrading from 1.5 to 1.7 - 2 errors :(


I've got a lot o trouble when trying to upgrade elgg from 1.5 to 1.7

1. Afeter uploading files (1.7) to 1.5 and running upgrade.php, there is a elgg logo on the center of the screen and after some time I've got 500 server error.... 

2. I've lost polish national signs in 1.7. MySQL backup application I use is 100% transparent, so the problem is in elgg.

I really need help :(((

Is there anybody who can solve my problems?

How long update should take? (I mean time from start upgrade.php to end)

(sorry for my english ;))