I have same problem - in my room it tends to go from 1 bar to full all the time - downstairs its goes from on to off all the time, rather annoying !
Got a brand new sim card so cant being that, but so many people
have complained about it cant be one fault handset - its just
faulty design maybe??
Why geeks like computers: unzip, strip, touch, finger, grep, mount, fsck, more, yes,fsck,fsck,fsck,umount, sleep.
HTC One Silver 32gb 
Nook HD+ 9 [CM10]
HTC Sensation [Vodafone, running cm10]
HTC Desire [T-mobile , Rooted, RCMixHD Rom]
HTC Diamond [Using Android 1.6 and windows 6.1]