Basically as above really!

I have a userform containing 2 TextBoxes that control dimensions within a SolidWorks model.

If a value is entered into the box all is ok, it works fine, however is the value is removed via backspace or delete the program crashes and I think it's (error 13??) that displays.

So all I'm looking at is making it impossible for the box to read nothing once text has been entered in it.

Also, is it possible to only allow numeric code to be entered as a value? I've not tried but I imagine entering letters would crash it too!

All help and advice is much appreciated!

Cheers

Greg