On this board I lost count of the number of times I heard this. Windows provides a port with number every time you connect something needing one. The problem is that in order to remember port numbers on say your PL8 or removable device it reserves these and keeps them so when you plug a thing in in future you get the same serial port number and the device still works. The problem is that many devices and much software only works with serial number up to 8 or 9.
So since windows reserves these first, for various bits of your PC and things that you plug in now and again they all get used up.
THIS little tool allows you to see the unused reserved port numbers and just untick them.
This is my laptop after unticking everything unused except for ports 13 and 14 that is actually my BT PL8.
The laptop itself is using ports 1 to 6 internally for its mobile internet, GPS, etc. So as soon as something "reserves" ports 7 and 8 then anything needing low port numbers is screwed and does not connect. Like chair programmers...
This allows you to get rid of any uneeded reserved port numbers. Its kind of self explanitory. And yes its safe.
This is the RESERVED PORT DELETION tool...