Rhino 6 Black Screen

Hi,
I unchecked all the third party plug in and restarted the system but nothing really has changed. moreover i have start noticing two others problem that I consider minor problems compared to the black screen:

1- when rhino goes black,some time, I am still able to access the command prompt and under system info I noticed that the driver information has disappeared. On the other hand, when rhino is running the driver version is correctly reported by the system report.

2- The issue It is totally random but it really happens more often when rhino is running in render or shadow mode.

3- few times i noticed as reported in other topics that lines or surfaces disappear from the view port but you can still see the gumball or control points acting on those curves ( attached img)

4- I have noticed when it crashes after I forced rhino to quit sometimes I receive the message that rhino failed to allocate the memory

here after pls see my attachments and error reports
November 27 at 07:30 AM in Rhino version 6.11.18323.19181:
nvoglv64!DrvPresentBuffers – Access Denied

November 27 at 08:15 AM in Rhino version 6.11.18323.19181:
0x0!0x0 – Access Denied

November 27 at 09:50 AM in Rhino version 6.11.18323.19181:
0x0!0x0 – Access Denied

November 27 at 09:57 AM in Rhino version 6.11.18323.19181:
nvoglv64!DrvPresentBuffers – Access Denied

November 27 at 10:49 AM in Rhino version 6.11.18323.19181:
0x0!0x0 – Access Denied

November 27 at 10:54 AM in Rhino version 6.11.18323.19181:
nvoglv64!DrvPresentBuffers – Access Denied

![Schizzo|690x388]