Tilde in English too ˜
You must use a leading zero before the number. On my character map it's ALT+0152 for ˜ Check your own Character Map under Accessories>>SystemTools. The Tilde can be a nasty one and can need a different keystroke under DOS in English, although its character code should be constant I think.
Jumping mice! Is the CPU over-busy when this happens and have you taken out the ball and cleaned out the fluff and gunge?