Sounds like you have a bad remote. Dtv will replace this if you are less than 30 days subscribed. They will probably cover it if you are less than 90 days, if you are insistant with them. Be sure to tell them that the cable remote didn't do this as you stated above, that will get'm going. Good luck.
If they don't cooperate, Walmart sells the Dtv remotes for $20.
It takes 2 to tango, but only one to be nice!, A/V Slave