Desktop 9, Win 7, erratically cannot extend desktop on multiple monitors in Win 7

I have a Mac Pro mid-2010 12 core with 34 GB ram, 2 GB video card, 4 24" monitors at 1920x1080. Running Win 7 with 5 cores, 6 GB memory assigned.

Sometimes I am able to open the VM and run coherence using all 4 monitors. Sometimes I get a message can't runs with this configuration. Windows displays settings may show 4 monitors (but sometimes not), but will not accept "extend desktop to this monitor". It reverts to disconnect. Sometimes rebooting changes this.

I have tried the settings in the KB articles in both OS X and VM configuration. These have not changed and seem to make no difference.

Help Needed!

 

Hi Blueridge,

Please follow the steps as suggested below:

1. (Re)Install Parallels Tools as suggested at http://kb.parallels.com/4841
2. Please follow the steps as suggested at http://kb.parallels.com/118728 to enable Extended Screen in Parallels Desktop 9 and let us know how it works.

 

Thank you for responding Ram.

I have tried everything suggested in your message, and I still get very erratic behavior.

Sometimes, when I open the Win 7 VM, all monitors show up in Display Settings, but "Extend" will not "stick" on any of the non-primary monitors when I click "apply" on any of them, sometimes only on one additional monitor . Sometimes, when I click "apply", all the non-primary monitors simply disappear. Usually in these cases the assigned resolution to the primary monitor is something unusual, not the native resolution of the monitor. Sometimes, when I boot the VM, there is only the primary monitor shown. SOMETIMES, "extend" works, and I get to use Coherence. All this can happen with no changes to any configuration settings from one time to the next.

It can happen in one VM, but not another started about the same time and running Coherence successfully. At another time that other VM will have the problem; again, with no settings changes in either the VM or OS X.

I have tried physically removing one of the monitors from the Mac Pro, to use only 3 monitors, but can still have the same problem.

This used to work very well until a month or two ago, and it has totally wrecked my work flow.

A solution would be genuinely appreciated.

 

Hi Blueridge,

Please follow the steps as suggested below:

1. Start virtual machine, go to Start → in the search box type devmgmt.msc and hit Enter (return).
2. Expand Display adapters and make sure that the is no exclamation mark and the adapter is called Parallels Display Adapter.

If these requirements are not met: right-click the adapter → Uninstall. If the pop-up appears, check Delete the driver software for this device and click OK. Restart virtual machine and reinstall Parallels Tools (in Parallels Desktop top menu bar go to Virtual Machine → Reinstall Parallels Tools).

If these requirements are met:

1. In Parallels Desktop menu bar go to View and check Use All Displays in Full Screen option.
2. Switch the virtual machine into Fullscreen view mode.
3. Go to Start → in the search box type Control Panel and hit Enter (return).
4. Go to Hardware and Sound → Display → Adjust Resolution (on the left pane).
5. Click the additional monitors one-by-one, and in the drop-down Multiple displays menu select Extend these displays for each of the monitors.

If the issue still persists:

1. Switch virtual machine into Window mode.
2. Drag and drop the virtual machine window to the 2nd monitor.
3. Enter Full screen mode mode and let us know how it works.