Originally Posted by autophile
Is OmniOutliner calling home? If so, can't it do this in the background instead?
I'm not sure why this might be happening. There are a couple of network operations that OmniOutliner can do at startup, though they wouldn't normally cause a stall.
The first is license validation - checking to see if the license is already in use. This check happens in the background, and just searches the local network - it doesn't check in with Omni at all. However, this process does begin by looking for licenses in several places in the filesystem, and that search may well not occur in the background. Those locations are ~/Library, /Library, and /Network/Library. These correspond to your home folder (for personal licenses that can only be used by your user account), to a global location on your computer (for licenses that any account on your computer can use), and to a network location (for licenses that are shared by multiple computers, such as in a corporate environment where the company has purchased a multiple-user license). I can imagine possibly the network location being slow depending on your network configuration.
The other thing is checking for updated versions of OmniOutliner, depending on your preferences. By default this is done once a week if you have it turned on, though you can change that. My recollection is that this happens in the background as well, and I wouldn't expect it to happen frequently - certainly not one every launch.
There are a couple of things I can think to try. First, change OmniOutliner preferences to not check for software updates to see if that fixes the problem. If it doesn't, try uninstalling the trial license and running the app in demo mode and see if that helps. That one is less helpful, but if it _does_ fix the problem, it's useful information.
Then I suggest using the "Send Feedback" item in the Help menu to submit a support request. The support team may have a better answer, especially if you have the results of turning off the software update check and removing the trial license.