Cannot get video signal out of Acer Aspire

I need the vga signal for my ACER projector. Aspire offers the utility eManager for this, but already there I see the problem. In this GUI it does not allow in "Display Device Switching" switch from LCD-panel-only to External-monitor or Both. Actually it does but has no effect and when reopening it is back again. It used to work, but somehow all of a sudden it stopped.
I already tried to reinstall eManager and also the vga driver for SIS M661MX.
It appears to me as there is a trace of stupid setting to LCD-only, which cannot be accessed through eManager, but should be manually changed in some setup file.
Or there could be some other utility, which could access the video hardware ?
Any help would be great as I cannot use my functional projector (tried with other laptop and it worked of course)

 

Adjust your interal LCD resolution to 1024x768 or some other equivilant 4:3 resoultion. LCD's hate widescreen.

--ssx--

 

Not sure I was clear. Btw it is about Acer Aspire 3630. The LCD on the notebook works fine, it is just the signal for an external monitor, here data projector Acer PS100S, which is blank. The ACER eManager utility even offers setting into either XGA (1024x768) or SVGA(800x600) in eManager->ePresentation setting, so there should not be a problem - of course, question is whether it takes it into account. The problem is another setting inside eManager, i.e. eManager->eSetting->Display Device->Display Device Switching. In this panel I cannot switch from LCD-only radio-button into External or Both radio button. This resistance does not produce any error so one does not know where the problem is.
I wonder whether there is another means, which can access/program the vga chipset other than through eManager utility. Or whether one can access a data settings in some other way.
One of the eManager setting is inside BIOS, i.e. eManager->ePresentation->Display Device->Boot Display Device. This seems switching fine, but I don't need to control it. It only proves that the video signal generation hardware is fine, because here setting it to Both generates video siggnal on my projector during boot up for few seconds and then when Windows starts it is gone. Behaves exactly as set in the other setting, which resists controlling