If you are having problems with popup menus and tooltips or windows that can't be resized then this is most likely due to the window manager you are using or the way you have configured the window manager (CDE, ctwm, fvwm, sawfish, metacity, ...).
Running out of disk space? Problems with your quota? First make sure you have at least 65000 kbytes in quota -- if you don't, you are not registered for this course!
Then, check the Resin logs. Resin stores its logs in ~/resin/logs and/or ~/resin/log. You can safely delete these logs.
IDEA has a built-in version control system which most of you probably never use. This version control system can potentially use up too much disk space. You can delete the files in ~/.IntelliJIdea60/system/vcs to reclaim this space. Then you can use Project Properties | Local VCS to decrease the number of days this history is kept (or to disable it altogether, but keeping one day of old history is probably better).
You can also delete anything in ~/.IntelliJIdea60/system/caches, ~/.IntelliJIdea60/system/compiler, and ~/.IntelliJIdea60/system/jars. These files will be recreated as necessary.
Make sure you don't delete these files while IDEA is running!
Can't run a shell command after adding a module? After
adding the module, you might also have to run the built-in shell command
rehash to make the shell update its internal caches (otherwise it
might not find the commands that are in the "new" part of the path that was
added by the module command.
Can't connect to the JDBC database? The
Connector/J JDBC driver class is named
sure you have included the Connector/J JAR file in your class path, as described
at the beginning of the project instructions! The JDBC URL should be on the
jdbc:mysql://[hostname][:port]/[dbname], where you can
probably omit the host name and port to make the driver connect to a database on
the same computer.
If you are using IDEA and you can't navigate in the completion popups using the arrow keys, this is due to window focus problems in your window manager, or due to using sloppy focus instead of click-to-focus. As a workaround, it is possible to disable the popups or increase the delays before they pop up using the IDEA option dialog.
Does the web server say that your servlet is currently unavailable? This may be because the servlet previously threw an exception. The server may remember this and prevent you from trying to run the servlet again. Try restarting the Resin server.
If you can't configure multiple servlets, make sure you place all the <servlet> sections before all the <servlet-mapping> sections.