Treeview Node Backcolor Not Setting

I have a treeview containg a hierarchy of fire stations with child nodes being the trucks in the stations. I drag and drop trucks into listboxes that represent incidents. All this has a SQL Server DB behind it. As the trucks are logged into the incident a SQL notification returns the update and I use recursive call code through the nodes to set the backcolor of the truck node to red, (not available). When the truck is released from the incident the same process sets the backcolor back to empty,(now available). The code works just fine until. If you exit the screen and then return back to the screen suddenly the setting of the backcolor no longer works. The code runs as I have stepped through it and the line setting the backcolor is processed but the display in the treeview does not change.I have tried, after finding the node making it the selected node and using the afterselect event to change the color. That worked until exiting and reentering the screen I found that the afterselect event did not fire after setting the selected node.When you enter the form with the tree view the tree view is rebuilt each time taking data from the database and presetting the backcolor for any trucks already involved in an incident.If you completely exit the application and start up again there is no problem with backcolor settings, the problem is only if you stay in the application and exit and reenter the form with the treeview.I am using VS2008 and I have tried the application on Windows SBS 2003 R2, Vista Premium and XP Professional all with the same result.