It happended to me just after installing the latest version. I am not sure,
though, if these strange characters were already in the file before.
It was an ini-file, and the corresponding program just ignores such lines, so I 
can't say for sure how long they have alresdy been there.

It may be an issue that only happens when editing several files side by side.
The reason I think this is the case is because this inserted text contained,
embedded in the garbage, some short segments of text that obviously came from
another file that I often edit in parallel.

PSPad freeware editor

Odpovedet emailem