COM port conflict

​I have an Inspiron 2650 (WinXP pro) and after encountering a problem with Hot syncing my Palm Handheld, it appears I have a conflict on COM Port 3 being used by another device. According to the Device Manager, COM port 3 is used by my Actiontec Modem. I ran the Dell Diagnostic software for my internal Modem and it also reported a COM port conflict. Strangely enough, the Device manager reports no conflict. In fact, it doesn't even show my Palm device. I have unplugged all peripherals (mouse, scanner, camera, etc.) except for the printer and te Dell Diagnostics software still report Code 67: COM port Conflict.​

​By the way...my modem works just fine!!!!​

​How do I troubleshoot this apparent conflict that doesn't show up anywhere but with the Diagnostics software or in querying my Palm Hotsync Manager?​