I am having a similar problem with my Eris.
My wife's Droid works fine.

My Eris sees the network and tries to obtain an IP address, but doesn't connect.
When the problem started, it would connect for about a minute, and then disconnect. Now it won't connect at all.
Technical support (Verizon and HTC) didn't know what to tell me.

I am able to connect to non-secured Wifi (such as the nearby coffee shop).

 

Well, I just reset my AT&T Uverse router for the second time to factory settings and changed the password.
It seems to be working, for now.

 

How far are you from the router? Does it stay on the obtaining IP Address status... Try doing a battery pull...

 

I tried the batter pull and such, but my Eris won't connect to my secure wifi network no matter what I try. I'm in the same room as the router too, so signal should be perfect. Any other ideas?

 

Is the router set to 802.11n only or 802.11a (I doubt that, but had to ask)? The Eris supports 802.11 b or 802.11g only. If you have an "N" router, you should be able to set it to mixed mode, so any client will connect at its fastest speed.

 

No, its an older A and B router.

 

Which security method are you using (WEP or WPA)? Have you checked to see if the router manufacturer has a firmware update? And, which brand and model router are you using?

 

its WEP, no firmware update and the router is 2Wire. My previous phone the Samsung i760 had no issues with this at all.

 

Are you hiding the SSID? If so, try it with the SSID broadcasting. I believe that Android has an issue with connecting automatically to hidden SSIDs.

 

I am pretty sure it is not hidden as it shows up on the list of networks available on my phone.