Sluggish touchpad after connecting ext HDD

[patkim]

On my vaio netbook vpcyb15ag when I plug in ext USB hdd ( IDE to USB box with its own ext power supply ), touchpad becomes too sluggish to operate. Usb mouse if connected also becomes quite slow. Any mouse pointer settings in control panel are also ineffective.
Things return to normal after USB hdd is removed and laptop restarted.
No such issue faced on desktop though.

What could be the issue. Is this USB power related and why would touchpad be affected?

 

[slashragnarok]

Try booting into safe mode and see if you can reproduce the error there. Then report back.

It would also be a good idea to check Power Options in Control Panel and see if High Performance is checked. If it is try switching to Balanced and restart your PC.

 

[SaiyanGoku]

Are you using the laptop plugged in or on battery?

 

[patkim]

laptop has been plugged in. also tried safe mode and various power options including Balanced.
touchpad continues to lag beyond usage no matter what when ext usb hdd connected.
even same results when i boot into live linux mint. Here the only difference was that the ext mouse was slightly better than windows!
I have a USB DVD writer that runs fine just off a single USB socket on the same netbook. so puzzled as to where the issue really is.