[GNC] Gnu Cash / UNrealised Losses in Trial balance

[Eid Eid]

HI to all.
I am getting an amount as Unrealized losses in my trial balance, and this is popping up while enot being related to a given registry/account. It seems to be generated by the system, and by playing around, I am convinced it is related to Difference of Exchange.
Can someone explain to me what this is, and how to get rid of it?

Thank you,

Eid E. Eid