http://www.asio4all.com/ I just went to it.
I would try out Craig's advice above, except I happen to disagree on disabling the on-board sound. (I would only do that it there was a definite conflict, otherwise, my recommendation is to assign your on-board sound as the Windows Default Audio Device, and only let your music production programs get access to either your audio interface or ASIO4ALL - I also turn off all Windows sounds, but that is just a personal choice and not any requirement).
Something to consider. IF downloading the drivers from the link someone posted above don't work, and you decide your current audio interface really is toast, then I would suggest you consider picking up a basic but good audio interface, rather than using ASIO4ALL and buying a USB/midi adapter.
My rationale for this is that a USB/midi adapter can run from a low of maybe $30 to $50 or more, while a good quality but not feature rich audio interface can start at only about $150-$200.
A new basic audio interface would not have more than a couple of inputs (usually mic/instrument), with phantom power and some decent analog/digital converters, but would be FAR better at keeping resource load of your CPU down, since it would take on the task of doing the analog/digital conversion, rather than making your CPU do it.
In addition, the new audio interface would also have midi in and out/thru ports, so you would be covered there, too.
So, the difference between the 2 options is something like $100 to maybe $150, and would give you years of MUCH better performance than the band aid approach of using ASIO4ALL and a USB/midi adapter.
Again, all of the above would be best evaluated only AFTER determining that your current audio interface was actually beyond salvage.
IF you end up going the ASIO4All route, then per the other poster's advice above, make SURE that you completely uninstall it once you ever get another audio interface, because it DEFINITELY can be problematic to have installed in the presence of another ASIO device.
I looked at audio interfaces from Guitar Center (
www.guitarcenter.com), and found one that I would suggest you consider. It is a Presonus AudioBox USB 2x2, runs brand new at $119.99, and gives you decent mic pres and converters, midi ports, and has drivers available all the way up to Windows 8.
Here is the direct link for that:
http://www.guitarcenter.com/Presonus-AudioBox-USB-2X2-USB-Recording-System-104841978-i1388074.gc I also looked at other available interfaces in the $100-$200 range, but many did not have either drivers for Windows 8 or if they did then they were missing midi ports.
I use the bigger brother Presonus AudioBox 1818 VSL audio interface, and have never had any issues whatsoever with it, and I am aware of others that are successfully using the smaller one I am suggesting you consider, so I have no reservations about recommending it to you.
It's pretty hard to beat $120 for a brand new audio interface with the features of the Presonus AudioBox USB 2x2. (from what I understand, the Focusrite pres may well be a bit better, but their $150 audio interface definitely does not have midi ports, though there is Windows 8 support for it).
Good luck,
Bob Bone