The SUBSTITUTE( ) function allows you to change some text to different
text, and so could be used, for example, to change "*" to "". A
composite function could thus be built up of
SUBSTITUTE(SUBSTITUTE(SUBSTITUTE( etc ))), but you are limited in this
to the nesting level of 7 so you could not eradicate all the illegal
characters in one formula.

A UDF could do it quite easily.

Hope this helps.

Pete