Client crash/freeze and mystery chars in calendar printout


3 weeks ago I upgraded from GW8 to GW14. Now I get notes from some users (especially ones which use multiuser calendar) that their Client does not respond anymore, like when they open an email and change the layout to HTML.
They also have problems when printing a calendar for themselves or other users. I found out that german umlauts in Jobs or Notes are crashing the Client. Even if there aren't umlauts, printout has a lot of "garbage" chars, always in front of the line and sometimes in the middle of text. Example:
●???? Start of line
●?•ØF Start of line
And some lines have these **** "overlaying" on some chars.

These problems are totally new.

Any ideas?