Object reference not set to an instance of an object

OUTLOOK:
Microsoft Office Outlook 2007 12.0.6316.5000 SP1 MSO (12.0.6316.5000) Security Mode: default

WINDOWS:
Microsoft Windows Vista Home Premium Service Pack 1, 32-bit

Here's the specific, reproducible behavior:
1. Shutdown Outlook 2007
2. Install reQallOutlookAddIn_setup.exe
3. Wait for 2 minutes, *without starting Outlook*
4. Error message "Object reference not set to an instance of an object" is shown
5. Start Outlook
6. reQall *is not listed* on my Outlook tool bar, or anywhere else in Outlook
7. Shutdown Outlook, uninstall reQallOutlookAddIn
8. Repeat steps 1-7

It seems that the addin does not work at all.

Hi Deb,
The problem reappeared I rebooted my system. Now there seems to be a cognizant pattern.

Normally, when my system boots up, it starts up 15 custom applications, including Outlook. Consequently, the boot-up process is rather slow (10-12 minutes before the system reaches a stable state). Applications such as Outlook do get launched in memory within seconds, but are inaccessible for several minutes. Additionally, my network connection takes several minutes to stabilize. reQall displays that error in this scenario. Perhaps "some object" in Outlook has not loaded (probably because it is starved of memory space or CPU time or network bandwidth), and reQall is looking for an object that is not yet in memory?

To confirm this, I prevented Outlook from automatically starting during boot-up. Instead, I explicitly launched Outlook several minutes after my system had booted-up and reached a stable state. Then there were no errors, and reQall appeared in Outlook's menu bar.

To verify this, I changed my system configuration to start just Outlook and 2-3 critical applications from amongst the 15 custom apps. This would theoretically, allow more startup memory and CPU for Outlook. This time, the system booted up much faster, and sure enough, reQall started with no errors.

I repeated the experiment by changing the startup set of apps to others a few times (to make sure that a specific custom application wasn't causing the problem). Each time the system booted up much faster, and reQall did not throw any errors.

To close the loop, I re-enabled Outlook to start at boot-up, along with all the 15 apps. The system boot-up slowed down as expected, and the problem with reQall reappeared.

I understand that the problem may not necessarily be because of a slow boot-up (memory or CPU starvation), but it's a place to start looking for it. Instead, It could simply be an undetected/rogue custom application (or applications) that's interfering with reQall, in which case, it's a different ball game.

Hope this helps.