noticed last night ITV2 and ITV3 were missing

did a scan and the channels were not picked up, scanned again and picked them up fine on the second scan

however I noticed MUTV and Sentanta 1 was missing, so did another scan and this time MUTV was picked up but no Setanta

DM500c, Pure NTHell area, running PLI Jade image

any ideas ? a signal issue

I may delete the services file and do another scan.