This sounds more like a hardware problem, than a software problem, unless you're loading old settings, that you have backed up.
The only way to test this is by doing a re-flash, and not loading anything else, including any backups. Instead you re-configure your tuner, to simple, Diseqc, A, B, C, D, assign your satellites, to the correct port, then do a scan, to load channels, and test to see if it's working properly.
If this fails try by-passing your Diseqc switch, by using a cable, directly from one LNB, to your receiver, re-configuring your tuner, then scanning ion some channels, and see if this works.
If this also fails then you need to try your receiver on a different satellite dish, a friends, or relatives, and see if it works correctly there.