problem with light pulse

[Kitanode]

Hi,
     I'm new to the US and trying to learn how to use all of it's different options.
Right now i'm having problems with the'light pulse' function.

I have tried to use it in both the learning example and my own exercises but it wont work.
When i press the light pulse button nothing happens.
I've tried looking all over the solar system for it but no joy.

Also when i press the 'light pulse' button my fps suddenly drops from whatever it's at to 3fps and stays there.

Has this happened to anyone else?
Have i maybe set one of the options wrongly?

I'm using the Steam version and it happens to both my desktop and netbook (Win7 64bit Ultimate and 32bit Starter)

ati 4770 gfx card

I don't know what other specs will be of use (dxdiag?) but just say and i'll post them.

Cheers.

[Kitanode]

I found an older post from this forum :http://universesandbox.com/forum/index.php/topic,3514.0.html
and after trying the different scenarios from it i have found that the problem happens when i run a simulation in realistic accuracy mode.

 If i put it in normal accuracy mode then it works fine so i guess i'll have to remember this in future.

However when i try the realistic mode my fps is still taking a severe beating from the light pulse and in fact on one occasion i did manage to see it far off in the distance behind and below the object i was using to trigger the light pulse from. It was so far away that all i saw was a small white pixel that didn't grow any bigger but i didn't know how to measure the distance or find out the exact location of it's origins.

If someone can tell me the best way to find out its location if i see it again then i'll do it, if it will help get to the bottom of this bug!

[vh]

I don't have Access to universandbox right now so this is just a best guess

turn down the dust multiplier to 1 or .5 if it isn't already

adjust the speed higher if you see a white dot that doesn't move

the distance on the bottom right of your screen
gives a vague indication of distance

If the object you fired the pulse is the largest in your sim, press home key to go to it

If the object is TOO large the light will get sucked in like a black hole