It's odd because both Wifi AND 3G don't work when it happens. It shows the correct amount of signal bars for wifi, and the 3G icon is shown as normal, but it just seems as if it's not processing the incoming or outgoing data.
I've tried plain reboots, clearing cache (and dalvik), powering off, battery pulls, permission fix, reflashing the ROM without a wipe, using Wifi fixer apps, toggling airplane mode, restoring just the "system" of an image that had no problems, restoring just "data", restoring just "boot", and waiting a day or two. It appears the only thing that will work for me is if I do a full system wipe, then reflash the ROM and restore just the data.
I'm pretty sure it happens sometimes when the screen is off, and (like the last time) when the screen is on. The last time I was browsing the internet with the stock browser looking up stuff about tea, and I stopped to uninstall an app, and when I went back the 3G/wifi were broken. That all occured within about 15 seconds, which is why I believe one cause of it is the uninstalling of apps.
The only things in my running apps list are the Messaging app, Settings, and SwiftKey 3.