BH, Let me say right up front that Java is not my strength -- I'm only a dabbler. One common reason for missing class file errors is having the class in a different directory than the applet or java bean that references it -- it's worth a check.
Since you don't mention seeing this error with Netscape clients, I'd guess you may be missing a class file that integrates some functionality of your virtual tour with Microsoft ActiveX controls.
I assume you have accessed your site with IE and not noticed any missing functionality, so it may not be worth the effort to fix this. However, a missing class file certainly can be important -- I'd turn to the author for a definitive answer.
By the way, I did a search on Google for panoBeanInfo.class and came up with only one page -- someone's web-enabled error log with an entry for the same problem you're describing! Google will index anything.