How do I change a file's type (specifically to "all files")?

I play the game Minecraft. I mostly play on my laptop, but sometimes I play on my Mom's desktop. I used to only play Minecraft on my Mom's desktop, and everything was working fine. However, today I have been having problems. In the game, there is no lag or anything, but after a while, a message comes up saying "Minecraft has run out of memory!". At first, I thought it wouldn't be a problem after the first time, but it kept happening. After about the 3rd or 4th time, a different message came up giving a thorough explanation of what happened. I copied and pasted this entire message into Notepad. I will attach this file so you can look at the message that came up. This file also said to see a full error report and gave the link to it. I copied and pasted this link into the Start Menu under Search programs and files. I will also attach this link. I went to a Mojang technical support resource forum and found the error I was having. Go to this link if you want to see what it says (Mojang | Minecraft has run out of memory). I followed the instructions, until I got to the changing the file type part. Because I could not figure out what to do, I skipped this part and went on. However, this did not help. Minecraft crashed again and I got the same message. Thank you for reading and if you know what I should do, please help. Thanks!

I am not a Techy so I am only going to give you tips that may or may not help but they won't harm the pc so all you will do is waste a little time doing so.

You may want to do a Windows Update if you haven't done so in a while (silverlight may update with win updates)... you also may want to update your codecs (google K-Lite codecs if you don't know how to update them)... then update your flash, shockwave and adobe air, Audio and Video Drivers and finally your Java.

Again, it may not help your issue but it will help for other things... hopefully the more savvy pc gurus here will shed some light on the subject.