Dont allow to start application installation if CCMSetup.exe is in progress.
1. PC is waiting on Maintenance window at Monday 4:00.
2. Monday 4:00 starts ccmsetup tu upgrade ccmclient (MSIInstaller is in use)
3. Monday 4:00 starts also SCCM Application to install (Installation fails with 1601 because MSIInstaller is in use by ccmsetup->client.msi)
Step 2 and 3 should not happend asynchronous.