If you have a yellow circle and an exclamation point next to a COM port, in Windows 2000 Device Manager, the General tab of the COM port Properties may display:
This device cannot find enough free resources that it can use. (Code 12)
even if the COM port is not being used.
NOTE: You may have to remove attributes to edit the boot.ini file. Type attrib -r -s -h c:\boot.ini at a CMD prompt.