quotation problem

I have a site with a simple admin tool (cut and paste text into a form field etc)

Problem is, whenever someone copies in text with quotation marks, dollar/pound signs and then
submits it to the database, the text shown on the front end contains ? marks instead.

I have read this may be due to special characters or something, is there anyway to stop this
happening or filter it out as the admin is for general use by registered people.

thanks for any help