PHP error - can't update modules

I tried to update Views, Imagefield and Quick Tabs modules but I can't run update.php

I get the following error:

An unrecoverable error has occurred. You can find the error message below. It is advised to copy it to the clipboard for reference.
Please continue to the error page

An HTTP error 404 occurred. http://www.123.abc/update.php?id=15&op=do

Invalid argument supplied for foreach() in /home/abc/public_html/modules/system/system.module on line 883.

The mentioned line 883 is:

foreach ($themes[$key]->info['scripts'] as $script) {

When I continue to the error page, there are following messages added:

warning: array_pop() [function.array-pop]: The argument should be an array in /home/abc/public_html/update.php on line 314.

The update process was aborted prematurely while running update # in .module. All errors have been logged. You may need to check the watchdog database table manually.

Well, this message was already displayed before, but I could have run updates without any problems. I tried one of the mentioned solutions to run update.php in IE. It did the trick, but updates failed.

What's the problem? Everything was working fine few days ago and now I can't update a single module. :(