Re-installed updated firmware from CD, this time selecting to overwrite corrupted config file on the Pronto with default config file from the CD. Presto!--this finally unblocked the remote and I am now back to square one: functioning Pronto, no devices. Before making new attempt at download, wondering what I should do to avoid repeat of the problem. "TSU 7500" has definitely been selected in PENG, so don't see how there could be incompatibility issues. Any suggestions, more than welcome.