Do you have url_fopen enabled in your php.ini settings?

Yes :)
allow_url_fopen On On

Can i download the plugins from market, and upgrade them manualy ?

Yes, you can. But I recommend you to find the reason of this error cos autoupdate is a better way.
Would you enable debug_mode in ow_includes/config.php file and try autoupdate again? You will get an actual error in this case.

No error in debug mode.
Only getting this error.
"admin+plugin_update_download_error" when i try to install / download plugin.

When i try to upload a plugin i get this error.
"admin+manage_plugin_add_extract_error"

Somthing has happend here... and i don't know what.
Need to check and do some test.
If you don't have any solution.

I think i found out what was wrong. It was my ftp info or chmod rights.
Did a recursive chmod on plugins folder, and changed my ftp info.
Then it works.
So this is solved. :)
Thanks anyway.

Glad to here that you are Ok :)