no more continue dimensions

[bstk]

I'm having a dimensioning problem which has suddenly occured in both new and old drawings (acad 2002): I'm not able to make continue dimensions anymore.
If I select an existing dimension, and try to set some continued dimensions next to it I get a message 'Extension line origins cannot be equal.' When trying so, I get a 0 number for measurement when moving the cursor.
It happens in both vertical and horizontal directions, even with osnaps off.
Anyone please?

[bstk]

It's driving me nuts! Can someone please help me?
Sometimes restarting helps, but it keeps coming back.

AAaargh!

[Spageddie]

I've trying to find information on this issue but I can't seem to find any.... At what point does this happen ? is it random ?
Can you post a screen dump (or email it to me)of the message you are getting. ?

Does this happen if you use different dimension styles ??