1. In Internet Explorer or ALM Explorer?
2. I used to get this kind of messages on the first attempt to select the Defects module. However, the second attempt to select the module was successful.
OTOH, depending on the moon phases, I used to get a message like ''Object reference not set to an instance of an object'' on every single mouse click in the Defects module. I can't remember on what patch version I was at that time, but these are the current versions (which seems to behave a little better in the Defects module):
* HP Application Lifecycle Management 11.00 Service Pack 2 Public 11.0.0.5761
* Enterprise Integration for SAP applications 2.6.0.3232