The "frozen cursor" quite probably is due to a failure of the PnP (Plug-And-Play) utility to "find" the speakers when they're turned back on and to assign them correctly. Quite possibly, the audio is getting an interrupt (IRQ) assignment conflict with the mouse that stops the mouse from working.
There are few practical remedies for this situation (if it's what's happening). PnP is pretty good at assigning "workable" configurations at bootup, but a new "serial" device added after the machine is running is a very real problem, and sometimes it just doesn't work.
When the speakers are turned off, the "assignments" they had may remain registered with the OS, and when they're turned back on the computer can't use the same one(s) since the computer doesn't know this is the same speaker set that went away and then came back. The computer must "install" it as a new device.
If there isn't another assignment "free" the "new speakers" can't be turned on, or a conflict is created that stops something else - or the whole computer - from working. Since there really aren't enough IRQ (or DMA) assignments available for a "modern" computer to run properly to begin with, it just doesn't work.
Overloading of the available IRQ and DMA assignments is one of the reasons USB is so popular, since it allows multiple "serial connections" to share one set of IRQ/DMA assignments, using what amounts to "device names" to separate things. To some extent this amounts to just giving the problem a new name and a different haircut for disguise purposes; but it at least produces a "slightly more tractable" set of problems for the current overload of plug-ins.
New USB devices can generally be plugged into a computer that's running. Most require (or at least benefit from) using the "safely remove" utility to unplug them. Older "plain-vanilla serial" devices need to be in place and turned on at re-boot to be reasonably assured of a working connection. Disconnecting and reconnecting one serial device usually(?) makes the computer provide hookups for two devices, the old one that it thinks is still there and just being quiet, and the new one that suddenly appeared. Often, there simply isn't a "safe" connection available.