Heck...Parser error all of a sudden

Newbie in Sharepoint I got this error... Immediately afterwards, I had to say OUCH... That's because I simply did nothing to get an error... I was only trying to create a new master page to use... That's all :))
I even undid any changed and still the error was there...
It said the following:

Parser Error Message: Data at the root level is invalid. Line 1, position 1.
Source Error:
Line 1:
Line 2:
Line 3:
Source File: /App_Browsers/compat.browser Line: 1

After some searching, I found the cause of this really strange behavior...
Some folders are created named "_vti_cnf" just beside the file "compat.browser".
This folder contained another compat.browser file containing some metadata. I
deleted this folder and this fixed the problem.

However, I hope this doesn't cause more troubles... If I find out anything, definitely I'll post it here :))