Copying text in PDF sometimes pasted as gibberish.

Hi All,

Sometimes when I copy and paste text from a PDF file into anything, the pasted text becomes gibberish in the form of "Максимален капацитет" (for reference this text means "maximum capacity"), or cannot be pasted at all, making me have to waste time copying text again with the hopes of it pasting properly.
I initially thought the problem only occured with cyrillic characters, but the font I use, Minion Pro, supports cyrillic.

I suppose I should emphasize the fact that all this happens when I copy- paste text sometimes. The odds are 1 to 3 on whether the text is pasted normally, pasted in gibberish, or not pasted at all.