Wireless sometimes can't be detected?

My computer recently has been having some problems with my home wireless.
The modem and wireless itself is fine, my iPhone can connect to the internet no problem.
But once in a while, even when I'm in the process of opening some websites, the Wi-Fi suddenly springs up a limited access yellow triangle. And when I disconnect the limited access triangle, it can't detect any networks at all (There's usually a couple of wireless networks in my neighbourhood that I can at least detect).
It's not a big problem, because after I go through the network troubleshoot to restart my wireless adapter it works fine.It's just that it has been happening daily now, and I'm confused as to why and how can I stop making it happen.
The only recent change I can possibly think of I made to my internet is that I replaced my home internet dsl scrubber.

Added (1). EDIT: My bad, I meant that the only thing I did was I replaced my internet adsl filter.
Just to ask, if I do buy a new network adapter, is it possible for a lay person to install it herself? I have never ever opened a PC harddrive before.

Your DSL and Wireless signal is separate (unless the same device)

Your experiencing interference… Could be when a Microwave turns on… The pipe between your wall… A very large mirror… Fridge, another Wi-Fi signal… (see if there's an area in your house where the connection is strong… If not you will have to run an access point to the area your experiencing bad Wi-Fi connections to build a new strong signal)

But if your only experiencing this problem then your probably have a bad network card… Get a new one.

---…

Well but at one point you still had internet… So ISP…

but could be your NIC Card…

Just buy a USB one that just connects to your PC… Install drivers and plug in devices then you can take off and put back when ever you want. Without opening up the PC's case.