Unable to switch to Coherence

From my experience with this issue it is a combination of resolution and virtual machine video graphics settings. for example, if I had my video graphics for the VM set to 256mb and my resolution on my screens set to the highest possible, coherence will not work and if i have my VM graphics set to 64mb and resolution at the highest on my screens it works ok, works in reverse also.

I would like to run at a higher graphics memory for 3d acceleration but i suppose this is a hardware issue rather than an issue with parallels itself.

Hope this helps

Nathan
 
Coherence on more than 2 display

Anybody able to use Coherence with more than 2 display ?
I'm using iMac 27" and 2 Dell 24". Coherence worked only if I remove one of the Dell.
Otherwise I get Unable to switch to Coherence error. I tried also changing the Video memory on the VM still no luck.

Tony
 
Hello Tony.
Please check if you have any other video drivers installed - open your VM, go to Start > run> devmgmt.msc > check video adapter - there should be only Parallels video adapter installed. If you see anything else - remove it (make a snapshot before - just in case).
 
windows 7 was showing 2 monitors for some reason both of which were not called parallels vu. Heres what i did, goto device manager in windows 7, , disable the generic vga monitor that appears there, then right click desktop and goto the displays, make the parallels vu one the default (after disabling the generic vga one the parallels one gets replaced by it) . Then enable coherence ... it now fully works.
 
I was the same problem. Was the anti virus!. In particular, Antivira. I desinstall it, and the problem disapear. I install Antivira once moré time, and the problem apear. I try to define exceptions in the antivirus, but do not word.
There is some incompatibility with several antivirus...
 
I can confirm this

Gustsanchez said:
I was the same problem. Was the anti virus!. In particular, Antivira. I desinstall it, and the problem disapear. I install Antivira once moré time, and the problem apear. I try to define exceptions in the antivirus, but do not word.
There is some incompatibility with several antivirus...
Click to expand...

My MBP could not start the BootCamp Windows in Coherence Mode. After deinstallation of Avira AntiVir it works.

So which Anti Virus software works well with Coherence?
 
Found a Solution

Using Windows 7 32 bit PRO + Avira Antivirus 2012 ( be it premium or free or Internet security suite)
Parallels desktop 7
Mac OS X Lion
Suggested steps didn't help , but found one definite solution:

in Avira
go to Configuration
enable expert mode
choose general section
choose Security subsection
in the right side uncheck the "Advanced process protection"

done!
Click to expand...
Source http://forum.avira.de/wbb/index.php?page=Thread&threadID=137710
 
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