DirecTivos can do funny things if they lose satellite signals. I suppose the easy fix is don't stand in front of your dish. Or mount your dish higher.
Sony SAT-T60 120GB (v3.5b)
HR20-700, HR20-100, HR21-200 HD DVR
HR10-250 HD DVR 400GB (v6.4a)
H21-200 HD Receiver
R10 DVR 160GB (v6.4a)