system restarted with messages "Error adding a request to the dispatcher ""

Hi,

Today ECC system restarted. The following error messages were found in SM21

" Error adding a request to the dispatcher queue ( UP2)

Request (type UP2) cannot be processed "

I cheched Queue information for this system by navigating to Goto-->Server name --> information -->Queue information

NOWP     0     21     2,000     25,181,608     25,181,608

DIA     0     13     2,000     3,384,734     3,384,734

UPD     0     29     2,000     185,673     185,673

ENQ     0     69     2,000     18,928,082     18,928,082

BTC     0     0     2,000     0     0

SPO     0     3     2,000     5,539     5,539

UP2     0     2,000     2,000     107,232     107,232

This is the first time a error of this kind is noticed. Can some tell me what could be the root cause and how to fix this issue?

Regards,

Chaitanya.