Like Chris has stated, this could be indeed a hardware issue & is appearing as such, it could be that the supplied drivers temporarily restored the device to semi working condition, but the same issue has returned. Yes these wireless units fails for varying reasons, as evidenced by the high numbers of used (& sometimes new) replacements sold on online auctions such as eBay, or other sources such Amazon & Newegg.
I'm sorry to hear that the wireless card is causing further problems.
Fortunately, this doesn't have to be an expensive issue to fix. As Chris stated, there are several brands to choose from in the $20 range, though I suggest not to go too cheap (you get what you pay for). The ones for less than $12 or so, in general, aren't worth the time of day, will often run hot after a few minutes of use & Internet connection will be very flaky. Make certain to obtain one that's designed for Windows 7 or higher. TrendNET is a brand I suggest you avoid (regardless of price), many who has purchased these has posted negative reviews & there has been at least a couple of recent Topics where the issue was an overheating one of the brand.
ASUS is a decent brand with much everything the corporations builds, ALFA is another known good one, so is BUFFALO. Here's a well reviewed one of that brand on promo. No recent negative reviews.
And several ASUS models. It's best to ignore any refurbished ones listed.
I would have linked an ALFA, but the ones on the Newegg site are from 3rd party sellers, haven't had good experience with the couple of "First from Asia" deals on the site that was purchased. There are many Non-Genuine clones of these available, the best way to obtain this brand are from authorized dealers. This greatly reduces the risk of getting burned.
One other thing, the ones as small as a wireless mouse receiver are best to avoid. The chipset is right there against the computer, where there's going to be more heat. Even wireless mice receivers gets hot sometimes & not perform as well on some computers, one reason why mine is plugged into a hub on one of my notebooks.
If this were my notebook, having found this manual (assuming it's the same one as yours), I'd replace it with the original or compatible one, access is easy peasy on this model, total of 5 screws to remove to open. Immediate access to the wireless card. Being that the ones of this model I've found are Intel based, I'm kind of stumped on why they didn't include an Intel wireless card. Maybe to save a few dollars or to keep the model under a certain price range.
Keep in mind, I have some experience on replacing these parts, and realize that some doesn't. Many are much harder to access, that's for certain.
One last thing I'd like you to try, if you haven't already. Does your notebook have the Power4Gear eXtreme option (Fn+Space Bar)? I ask because some of these power saving modes directly affects wireless performance. If set to maximize battery life, this will impede wireless performance & other things too. Here is the manual (Page 38) for your review, or you may want to check your own manual or go to the ASUS site for your documentation (which may be the same as below). This is an 11th hour shot in desperation, but I still say to check this setting out. Even if you replace yours with a USB one, performance won't be as good in these power saving modes. Because I run SSD's in my main computers, these are tuned to High Performance, regardless of battery or AC mode.
Edited by cat1092, 01 August 2014 - 08:15 PM.