Failed to install Tomcat service: solved

I spent about a frustrating half-hour solving this one. Tomcat 5 has such a nice Windows installer, and good integration with Windows services, so I hate to rag on it. But for such a common situation, it seems this is a vast oversight in the Windows Tomcat installation program.

The problem was with installing Tomcat 5.5.9 on a Windows XP system. I'd run the Windows installer and get this error dialog:
Failed to install tomcat 5 service
Check your settings and permissions
Abort Retry Ignore
The above is accompanied by a warning to select Ignore at your own peril. I googled around and none of the suggestions worked. The most common situation that results in that error is not being logged in with administrative privileges, since the Windows installer installs Tomcat as a service. That wasn't my problem. My login privileges was the first thing I checked after the "check your settings and permissions" message. I even checked the Tomcat bugzilla site and got the "Zarro Boogs found" when looking for my particular problem.

It seems the problem was having Tomcat 5.0 installed on the box. It appears that the 5.5.9 installer tries to install Tomcat as a service using the same service name, and gets an error from Windows that a service with that name exists. Either that, or the installer tries to create a Windows registry key that already was in use by Tomcat 5.0. At least these are my guesses, because uninstalling Tomcat 5.0 made the 5.5.9 installer happy. After the Tomcat 5.0 uninstall, everything worked OK.

It seems too bad I can't have both versions installed at the same time, at least by using the Windows installer.