Just joined up to post this. Ive been having the same problem with my EVO. And it's really annoying as Ive been having text battles with this chick and I cannot go back to back up my own statments. HAHA.
Anyway, I noticed that this problem only happens when the 3G indicator is going crazy. The up and down arrow are both lit up. This seems to be when I have problems scrolling. I tried every possible thing to fix it, landscape mode, deleting apps, rebooting, etc etc.
Here's how I fixed it:
First off, I wanted to know WHY my 3g indicator was going nuts when I wasn't really doing anything. Those of us (including me) who just switched over to sprint to get an EVO have only had our sprint service for a whopping 10 days. I just yesterday setup my online accound so I can start to pay my bill online. When I viewed my data useage I was ASTOUNDED that ONLY from the billing cycle start (the 8th, making that only 6 days) I had already used 2.2GIGABYTES worth of data. Now that's ridiculous. That puts me on target 8+ gigs a month, which in most moble services is unheard of. I'm an avid phone user, heavy use and even for me, that's out of this world.
So I started thinking what could be wrong. Only thing I could think of is the contacts / facebook syncing constantly as I have over 70 people (out of 250 contacts) linked via google and Facebook. The ones facebook didnt find automatically, I manually did, cause let's be honest, it's a kick ass feature. So I went through all my contacts and unlinked them both on google, AND on Facebook. I then restarted my phone and voila. NO MORE CRAZY 3G, no more scrolling problems.
Can't say this will work for everyone, but it sure did for me when nothing else would. I also can't wait to see in a few days how my data useage has changed... I'm willing to bet it goes down like a drunk teenage girl on prom night.