Have you tried using the 411 UTV code (when "off" enter 411 using UTV Remote, Pressing Menu-Options 3 times then 411 is optional, if 411 doesn't "take" try pressing Menu-Options 3 times first.) you should get a multi-color flash from the UTV's front panel and when powered up it should give you access to a hardware information screen. One of the items listed should be a Hard Drive ID/Model # next to "Storage:". If that is blank or missing from the list... the UTV isn't seeing the drive... You'd want to verify your power/data cable(s) are good and making good contact with the Hard Drive. (REMOVE ACCESS CARD FIRST!!! Opening the UTV Case may cause the Card/Card Reader to bend/break. Repairs can be done but it isn't fun...)
IF you do have a Hard Drive listed next to "Storage:" and the UTV OS is installed/running properly you should be able to access your UTV GUI (User Interface)
from the 411 info screen. Press Menu-Options (RCA) or Options (Sony) and from the Menu select HOME and it should take you to the UTV Home Screen. From there you should be able to access menus as normal...
Typically if you are unable to get the UTV to "see" the Hard Drive... it will just continue to look for the OS and not finding it... it will continue requesting to download it.
The usual fix for this problem is to replace the Hard Drive.
As you've already tried replacing the Drive at least once... this might be a Jumper setting issue (Master or Single Mode is best... on the earlier WD drives it was advised to PULL ALL JUMPERS... That provided Single vs Master Mode if I recall... hopefully the drive has Jumper Settings included for more detail.) OR possibly either a bad drive or non ATA-3 compatible drive (WD BB drives should be ATA-3 compatible... Try the "IBM" Drive Fitness Test program if you'd like to confirm ATA-3 and/or the drive(s) you have are viable... http://www.hitachigst.com/hdd/support/download.htm#DFT
IF the UTV was able to at least recognize or "Lock" the 80GB drive you could attempt to switch back to the old (40GB drive?) and have it "Remarry" to that drive... While if you were having problems with that drive it isn't usually a good idea to try it again, but it could be a good troubleshooting diagnostic OR you could attempt to "unlock" the drive for regular PC use (after running some a "fitness" test).
Recently saw a 320GB IDE Western Digital Drive at OfficeMax on clearance for $60. Kind of excessive for a UTV... but if you have any other smaller IDE Drives around (maybe 120/160/200GB... I have a 30GB ATA-3 Western Digital which "should" be UTV compatible) you could "upgrade" your PC's older IDE Drive and transfer all the data to the much larger drive (and use it all)...
Let us know what you discover/decide but it looks to me like a Hard Drive Tweak/Upgrade is due.