If there are multiple DHCP servers for a network available (in your case the controller and Windows), the first one to respond is where clients will get an IP address from.
First confirm DHCP is setup properly on the controller:
show ip dhcp database
show ip dhcp statistics
show ip interface brief (the controller needs an IP on the VLAN)
Second, if you cannot turn off the scope no the Windows server, you can configure a DHCP helper for the VLAN in question to try and direct the request to where you want.
interface vlan XX
ip helper-address x.x.x.x (IP of controller)