WiFi "Error" after installing Android 2.2

Had Desire for about six weeks, working fine on wireless network at home.

Downloaded and installed Android 2.2 last night (via WiFi) so it was working then. This morning, WiFi is turned off and when I try to turn it on, either via widget or on Wireless & Networks page, nothing happens.

On Wireless & Networks it changes to "Turning on..." for  a few seconds then just changes to "Error". Under WiFi Settings, Network notification and Add WiFi network are both greyed out and flash grey rather then green when pressed, so they're basically un-selectable. Selecting "scan" via the menu does nothing either.

Coincidentally (or not?) we also changed broadband provider yesterday. Android was downloaded via the new ISP but using our original Netgear router - we have now changed to the provided Sky router, but I have no idea if this is relevant or not, as I'm not sure exactly when the problem started.

Can't tell if the problem is with the phone or the router/network, however my laptop can see several other wireless networks from neighbours etc and the phone clearly can't see any of those. If the problem was with the router/network, I would imagine I should still be able to turn WiFi on and browse for available networks?

Has anyone seen this issue before? Any ideas/advice?

Anything you can suggest would be much appreciated!

I was hoping to avoid that, but had a sneaky feeling it would end up being the only option - thanks for the advice - much appreciated!

I'm out of ideas really.  Normally the reset should solve just about every problem.

As for the "Privacy" section, apparently they forgot to put the lnk in there.  It hasn't been moved around, it just can't be reached through the menu anymore.  You can find it via the phone's search app.  Just search for "privacy" and it'll show the missing page as a result. 
HTC is aware of the problem, but haven't said if they were working on a solution.   

Yip, just noticed that too on my own phone.  For some other members it works tho.  Time to dig deeper into this.

That still doesn't solve the WiFi problem tho.  Try to mail HTC.  Maybe they know some special trick that could fix it without having to take it to the store.

HTC messed up with my phone Sad
Turned it on, activated wifi and got a upgrade message to 2.2
 
Did that, and wifi worked for 3 days, now it just says ERROR.
Whenever I activate wifi it says error.

Tried to reset factory defaults, battery in/out, full charge and so on...
While trying different stuff, I found out that BT is not working either...

It's going back to the shop now...

Thanks Cirion, Wefi works well.

People, i bought my Desire with 2.1 and upgraded to 2.2 and it was working great for almost a day. Then Wifi just went ... rebooted, tried to connect to another Wifi spot, etc. and nothing.

Then i got a message saying there were three updates available??? I didn't know what they were so i cancelled but it kinda froze. I was unsure what happened so rebooted again and it seems to be working again.

Although .... i have an issue with texts being sent from the phone that i have not sent. I don't know if this is related though.

I'm also having this problem after upgrading to Froyo. Wi-Fi is just showing as "error", although I have no problem using my laptop on the same router. No wi-fi networks show up at all. MAC address is "unavailable". This was all fine before I upgraded.

Things I've tried:
Power on and off.
Hard reset
I tried the cache reset suggested by Cirion, but the phone froze when I got to the red triangle reboot.
Tried we-fi, but it can't find a wi-fi either
Tried to set the phone as a wi-fi hotspot, but I just get an "error" message. Tried messing about with the settings but to no avail.
Tried setting a static IP address on the phone, no success.

I'm going to try mailing HTC, but I'm not holding my breath...