Hi MiKonst,
With regards to the upgrade error, could you send us the error on the cache/log.php?
As for the reinstalling problem, this is related to the way MySql is configured. Could you check this?
The problem is produced when you insert a log and do not specify a column. If this column does not have a default value defined on the table, it fails.
You can check this so that it only gives you a warning instead of an error in these cases.
Hope this helps

Natalia