When your text goes wacky, open the console and type the command clearGlyphCache. It's worked every time so far for myself and a couple friends.

EDIT:
For convenience, you could also add a line like this to your autoexec.cfg:

bind "F9" "clearGlyphCache" "SHIFT"

Then Shift+F9 will fix your text.

ty for sharing, i am going to check it out

btw is it case sensitive ?
is there a help command to list commands starting with a wildcard , for example help cl*
?
ty

Commands and cvars are not case sensitive, I just use it for readability.

You can use wildcards, and also TAB will auto complete partial commands - try typing "list" then hit TAB. If it's just a trailing wildcard you want like in your example, you can even omit it. Try:

listCmds clear

...and hit Enter.