Cannot draw using mouse

I'll keep this thread running as it might help someone else.  I have decided that the problem is associated with the laptop PC graphics adaptor and will be talking to Lenovo shortly. The i5 CPU has integrated graphics (Intel HD 4000) and Lenovo has built in an Nvidia GeForce GT635M graphics card as well. It seems that I am having difficulty in convincing the computer to use the Nvidia processor, although this is by no means certainly the case. Sometimes I can go into the Nvidia settings and assign the Nvidia GPU to Draftsight and it will work. When it works, the Nvidia icon in the notification area becomes coloured ( to show that it is selected)  however, sometimes, the icon is coloured and Draftsight does not work, even though it is the only assigned program.  What I can say for certain is that, once I get it working, it keeps working unless I restart the computer. A restart of the computer stops it again.  I have managed to get it working on two occasions, now, and it was fine until I re-started the PC.  Currently it will not draw using the mouse and I cannot figure out what I did to get it working although I thought that I had simply assigned the Nvidia GPU to the software.  For those who are interested, here is some of the computer spec:

Lenovo Ideapad Z580

Intel i5 3210M  Processor running at 2.5GHz

Intel HD 4000 AND Nvidia GeForce GT635M graphics

8Gb RAM

1Tb HDD

By way of an update: I have now unistalled Draftsight, deleted all Draftsight references from the Registry and reinstalled.  It still won't draw using the mouse or touchpad (I can still draw a line or shape by typeing in the start and end coordinates). I have tried turning Optimus on and off in the BIOS and enabling Vizualisation (Vanderpool Tech) but it makes no difference. The Nvidia icon in the notification area colours up as the program starts, indicating that the Nvidia GPU is assigned to Draftsight. I really cannot get my head around how I originally got it to work and continue working for about three weeks until I restarted the computer.

I loaded TurboCAD Double CAD XT 5.0 and that runs without any problem so I regret that I will now be uninstalling Draftsight permanently. I will be happy to try again if anyone has any more suggestions but, for now, that's it.

This is weird. On Tuesday 9th Feb I opened up Draftsight as a demo to a friend of what was happening and I found it was working normally. I cannot think of any reason why that might be because I had given up trying to get it to work and was contemplating uninstalling it it favour of TurboCAD.  I have opened it several times since and it has been fine.  Today, I had to restart the PC after a Windows 10 update and, guess what, Draftsight has reverted to not drawing with the mouse/touchpad.  This is really frustrating especially as no-one seems to have any answers as to what is going on. Since before it started working, the Nvidia GPU settings have been at Default so I think I can now rule out the GPU settings as a cause.

Draftsight started to work again, the other day. This was coincident with a Windows 10 update notification, which started me thinking. Is it possible for the update process to trigger or change some settings which cause Draftsight to work again?  As soon as the update was loaded and the associated restart completed, Draftsight stopped drawing again.  It is not the first time that this has happened (Draftsight working when an update arrives). There has to be a clue there, surely.