Windows 7, multiple UAC problems

Hi,
I've been facing some problems with UAC for over a year. I tried solving it myself initially but failed. So I ignored the problem for a year as it didn't bother me too much, but need to get it solved now as it has come in the way of my work.

I'm using Windows 7 Ultimate x64 SP1 on a Dell Precision T3500 Workstation.

Everything was working great until one day I noticed something had changed when I right clicked on any shortcut icon:
The shield icon next to the "Run as administrator" option was missing and there was a new option there called "runasuser".

When I click on either option, I get this message:


I tried doing a system restore but it failed and on restart I got a similar message. System restore never worked after that. Also have trouble installing some applications and running some programs like team viewer or time trackers.


I'm also unable to change UAC settings here:
I can move the slider but nothing happens when I click the OK button. And the slider is back to where it was when I close and open the window again. But I was able to get around this using the program TweakUAC.

The resource monitor button in the task manager does nothing when clicked:


When I right click on a shortcut and clicked on Advanced properties, the options are always disabled. Even when I am on an Administrator user account.


These are the problems I noticed and appear to persist whether I am on a Standard user account or Administrator account. I believe they are all linked? I tried searching everywhere but was unable to get much info on this problem. It will really be great if somebody can let me know what's going on and what I should do.

Thanks in advance!

Thanks for the quick reply Kaktussoft. It was impossible to open an elevated command prompt as a Standard user like you had guessed. I got the same error message. So I logged on to the user called "Administrator" and could run the command normally.
Results:

I checked the other things that didn't work previously. but they are not working in the administrator user account too.

I didn't see UAC-prompt to confirm but just the error message. Also created new accounts and had the same problem. I will log on to administrator and create a new account and let you know what happens.

I created a new user account while I was on administrator account, but it has the same problems too.

I did as you said and this is what I got -

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\exefile]
@="Application"
"EditFlags"=hex:38,07,00,00
"FriendlyTypeName"=hex(2):40,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,\
00,6f,00,6f,00,74,00,25,00,5c,00,53,00,79,00,73,00,74,00,65,00,6d,00,33,00,\
32,00,5c,00,73,00,68,00,65,00,6c,00,6c,00,33,00,32,00,2e,00,64,00,6c,00,6c,\
00,2c,00,2d,00,31,00,30,00,31,00,35,00,36,00,00,00

[HKEY_CLASSES_ROOT\exefile\DefaultIcon]
@="%1"

[HKEY_CLASSES_ROOT\exefile\shell]

[HKEY_CLASSES_ROOT\exefile\shell\Open]

[HKEY_CLASSES_ROOT\exefile\shell\Open\Command]
@="\"%1\" %*"

[HKEY_CLASSES_ROOT\exefile\shell\runas]

[HKEY_CLASSES_ROOT\exefile\shell\runas\command]

[HKEY_CLASSES_ROOT\exefile\shell\runasuser]

[HKEY_CLASSES_ROOT\exefile\shell\runasuser\command]

[HKEY_CLASSES_ROOT\exefile\shellex]

[HKEY_CLASSES_ROOT\exefile\shellex\ContextMenuHandlers]
@="Compatibility"

[HKEY_CLASSES_ROOT\exefile\shellex\ContextMenuHandlers\CmdLineExt]
@="{9869EFB4-18E9-11D3-A837-00104B9E30B5}"

[HKEY_CLASSES_ROOT\exefile\shellex\ContextMenuHandlers\Compatibility]
@="{1d27f844-3a1f-4410-85ac-14651078412d}"

[HKEY_CLASSES_ROOT\exefile\shellex\DropHandler]
@="{86C86720-42A0-1069-A2E8-08002B30309D}"

[HKEY_CLASSES_ROOT\exefile\shellex\PropertySheetHandlers]

[HKEY_CLASSES_ROOT\exefile\shellex\PropertySheetHandlers\ShimLayer Property Page]
@="{513D916F-2A8E-4F51-AEAB-0CBC76FB1AF8}"

[HKEY_CLASSES_ROOT\exefile\shellex\PropertySheetHandlers\{B41DB860-64E4-11D2-9906-E49FADC173CA}]
@=""

[HKEY_CLASSES_ROOT\exefile\shellex\PropertySheetHandlers\{B41DB860-8EE4-11D2-9906-E49FADC173CA}]
@=""