Installer error????? PLZZZZZZ?

Question

First, I'm using XP pro
ok, whenever i install something like photoshop or java update, or any applications that i download to install, i always get this error "the windows installer service could not be accessed. this can occur if you are running windows in safe mode, or if the windows installer is not correctly installed. Contact your support personnel for assistance"
I tried these methods already:
-open msconfig and set it in safe mode or F8 when start up
-and one from an yahoo answer user :
{To resolve this issue, follow these steps:
1. Log on to your computer as an administrator.
2. Click Start, and then click Run.
3. In the Open box, type cmd, and then click OK.
4. At the command prompt, typemsiexec.exe /unregister, and then press ENTER.
5. Type msiexec /regserver, and then press ENTER.
6. Verify that the SYSTEM account has full control access permissions to the HKEY_CLASSES_ROOT hive in the Windows registry. In some cases, you may also have to add Administrator accounts. To do so:Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
a. Click Start, click Run, type regedit in the Open box, and then click OK.
b. Click the following registry hive:
HKEY_CLASSES_ROOT
c. On the Edit menu, click Permissions.
d. If SYSTEM is not listed in the Group or user names list, click Add, make sure that the local computer name appears in the From this location box, type system in the Enter the object names to select box, click Check Names, and then click OK.
e. Click SYSTEM in the Group or user names list, and then select the Full Control check box under Allow in the Permissions for SYSTEM box.
f. Click Apply, click OK, and then quit Registry Editor.
7. Restart the computer.

ANY OTHER IDEAS???

Answer 1

This usually happens after a virus / trojan, so i would simply install a fresh XP. (backup before what you need from C drive)

Answer 2

Install the latest service pack of windows xp

Answer 3

you won't have administrator privileges, and it could additionally be a concern with hardpersistent corruption or fragmentation. in case you have been before waiting to place in utility with none issues, you need to run CHKDSK /F on your hardpersistent, then run the disk defragmenter.

Answer 4

i suggest u to install Zonelabs Security Suite..

get it from http://www.zonelabs.com