It usually does help, yes. Did your problem begin after a particular download, or does your problem persist even though you have downloaded new ephemeris data over a period of time? Once in a while, we'll get a bad one (don't ask any of us why - we're all clueless) that throws the unit off. When that happens, you'd be better off without that data there at all. Until I hear back, I'll assume the latter.
If this happened after a particular download, just delete the ephemeris data from your unit, and while you're at it, you might as well get rid of all of the old stuff from your PC as well. Then grab some fresh data from TomTom.
On the unit: root directory/ephem/ - kill all 3 files in the ephem folder
On your PC: My Documents/TomTom/Home/Downloads/complete/ephemeris/ - kill all of the QuickGPSfix folders you find there. There will be one for every successful? download you've had. Old ones are useless, and given your situation, the current one may be, too!
Now, fire up Home and grab the latest one and see if that helps.