Deployer service "undeploys" when accessing CF admin

Running ColdFusion 8 developer version

For quite a while now, we've had an issue when trying to automate creation of new instances using Selenium. Manually, it always seems to work fine, but when automated it fails roughly 60% of the time. All I knew up until recently is that the pages would get the error "there is no web application configured to service your request".

Thankfully, this wasn't all that crucial, and I could mostly ignore it. However, I'm getting to the point that I need to automate the regular deployment of one of our CF apps.

In looking through the log (cfusion-out.log), I noticed today that the failures coincide with the following line:

"Deployer Service is undeploying watched URL file:/C:/JRun4/servers/cfusion/cfusion-ear"

After it "undeploys", which includes several more log entries, it appears to redeploy the same application. The whole process appears to take about 8 seconds, during which requests fail as I had experienced in the past.

Why does this happen?