OK so a friend of mine had this same problem and i figured it out. The directory changed. If your getting the 1723 error missing DLL crazy message. and after working like a mad man for 3 hours I figured it out. You see getting that error means it can't find the DLL it doesnt mean the windows installer is bad. So whats the problem you ask well somewhere in your registry Java thinks its installed in a place that no longer exist or is searching for the DLL files that are no longer where they were. I hope this helps it was such a pain in the rear for me. I just want others to have the answer.
So heres the solution:
1. Get on a computer running the same OS as you such as Windows 7, Vista, XP.
2. Make sure there Java is up to date and the update installs fine.
3. Go to the Java folder in C drive usually found under program files or program files x86.
4. Copy the Java folder to a usb stick
5. Copy that same Java folder to your PC into the Java folder but be sure dont to cope the Java folder in the Java folder you dont want C:/Program Files>Java>Java>Jre6 you want it to be C:/Program Files>Java>Jre6. Or what ever way it was by default which is how I had it. (C:/Program Files/Java/Jre6
6. Now restart the computer and try to run the update again it should work fine.
If this doesnt work which didnt for me and this is why. My friend tryed to install the new version of Java or a developer version into a different directory in the C: drive and then decided to just delete the folder or it failed half way though. So this is what I had to do to find it.
Use the copy of the good Java files to copy to the correct Java location and try these steps to get there.
1. Run RegEdit
2. go to edit>Find or press ctrl-f
3. Type java and search for everything
4. Now make sure you start from the top of the registry since the find function starts to look from where you are in the registry
5. You are looking for some Value that shows where the Java folder should be located you will find these values on the right side of the screen as you search.
6. Use the F3 key to quickly keep searching for the next java value
7. I think this is the key were the problem was:
8. When I looked at the value for this key it was:
C:\Program Files (x86)\jre6_rse\Java\jre6\bin\wsdetect.dll
9. So what I did was I made a folder called jre6_rse in my program files and copied over the java files I got from another computers.
10. This in turn let Java see the DLL it was missing and let me install the updated Java.
11. Now you could go in the registry and fix this value and tell it to look in the correct java folder but my fear was well if theres one key with this wrong location there may be more so I just created the folder and then it installed smoothly and everything is back to normal.
Windows Vista to Windows 7 upgrade:
As stated above the problem could stem from the upgrade and the registry still looking in an old path format for the original Java folder and it cant find the DLL's. Follow the same steps above and it should work.
Its a pain in the rear but trust me just use the find function in the registry and take your time find the value for the java folder pointing to the wrong place and just create the folder and copy the good Java files into it. Just make sure you copy it correctly don't double up on folders make it exactly like the registry is looking for.
These registry key spots have a location that Java looks for maybe it will help guide you in your quest.