Updates for Illustrator CS5 won't install

Hi. I'm using Illustrator CS5 and I found a problem (a secondary problem here) with exporting PNG files (some weird white or black lines appear in the output), so I searched and learned that updating might help. I tried at first by going to Help > Updates... but it failed; then I downloaded the update manually and run it, but it failed too, with the error code U44M2P7.

I'm using Windows 7 Ultimate 64-bit.

Thanks in advance!