Open it in Notepad, put rem before the offending line and save it again (as "autoexec.bat" between quotes to be sure to keep the extension. It's rem set tv dump flags = 10 then.
Or (even easier) use msconfig to disable the line.
Then reboot and see what goes wrong. Nothing serious, I'm sure.
To save yourself this kind of problems: set the file to read-only. Some program installs might fail, but then you know what it's all about.
Hope this helps.
While checking to see what was listed in Autoexec.bat, I noticed a new entry underneath a pencil sign
with a check mark on the left hand side that says: Set tv dump flags=10.
I have no clue what this is and was not here a few weeks ago when I looked in the autoexec bat folder in msconfig a few weeks ago.