Try adding the following option to your graphics before exporting them...
BaseStyle->{PrivateFontOptions->{"OperatorSubstitution"->False}}
I'm not sure whether it'll fix all of the problems you're seeing or not (since
you didn't provide an example, it's impossible to say), but it helped with the
examples I tried.
Sincerely,
John Fultz
jfu...@wolfram.com
User Interface Group
Wolfram Research, Inc.