Thank you for your post.
There should be no difference between FileMaker Pro 9 and FileMaker Pro 10 when it comes to Instant Web Publishing.
In case there is a conflict, run msconfig and disable all non-Microsoft services. Then, after rebooting, launch FileMaker Pro 10 and turn on Instant Web Publishing. If this works, then you'll need to determine which Service is causing the problem.
If this doesn't work, then I would uninstall FileMaker Pro 10 and reinstall.
I have a Dell machine with Windows XP recently upgraded to SP3, but it has been running Instant Web Publishing successfully with both FileMaker Pro 9 and FileMaker Pro 10.
Have tried the disabling route (no success) and the reinstalling (no success). I installed on a separate Dell (with far fewer applications) and no problems, so rather obviously I've got something I didn't find on the original machine that conflicts with FM 10 but not FM 9.
Thanks for the help; I'll sit on it awhile and congitate.
Thanks TSGal, actually yesterday I installed blue stack software and caused this error but when I uninstalled that software its working fine.
Thanks for your best answer.