I tried to add a file through my profile in one of my sites and was trying to add this at first using Google Chrome to upload. After trying to upload the file a couple of times I decided to give it a go with IE8 and I found out that the same file with the same text went to my profile without any problems.

I checked the event viewer but found no related entries to the above described issue.

DNN544 / AS171

Try refreshing the page. I've noticed the same behavior with chrome too. I'm not sure what it is yet, but refreshing the page works.