lose hd channels while recording hd. New hr24/200

[idunno]

Have a bad B band converter already, just installed on 1/30/11. Have slim3 with multiswitch with 4 inputs, and 5 outputs and hr24/200 dvr. If record an hd channel, get 771 error on the rest. I know b band converter bad per troubleshooting, just hoping no other issues. Tech support fools keep telling me I don't need b converters at all!!!! Have converters being shipped, after having to call cancellation dept, but want them now, can I buy one at a retail store???? Also, do the unused outputs on the switch need to be terminated? Thanks