Grisoft's AVG Free Edition (latest build anyway) uses PSAPI.DLL build 5.00.2134.1 in its own directory. I noticed that the version in my %windir%\system directory was 5.00.1641.1. The latest restributable version on the Microsoft site seems to be 4.0.1371.1.

I replaced the version in my system directory with the newer one from the AVG Free directory by simply copying it over, after backing-up the old version. All seems well.

In general, is replacing system files with newer version as simple as that? Should a batch file also be run, to properly register the new file? Would the careful thing to do be to use something like Dependency Walker to first determine what other files may be affected by replacing PSAPI.DLL for a later version?

This may show wishful thinking, but: because this newer version of PSAPI.DLL comes as part of a freeware package, does anyone know if this newer version is able to be redistributed freely, thus superceding the version listed above at Microsoft?

Thanks in advance.

Edit:

I've since found this semi-recent thread here in these forums:

http://www.msfn.org/board/index.php?showtopic=56682

The dispute about whether build 5.00.2134.1 could run successfully under 98 SE didn't seem to be resolved. Has anyone had any further experiences?

Edited December 13, 200520 yr by bristols

Windows XP SP2 contains even newer version 5.1.2600.2180 (xpsp_sp2_rtm.040803-2158) and it seems to have the same dependencies - and the same missing functions in it.

MS DLL database http://support.microsoft.com/dllhelp/ contains many different versions but nothing for Windows 9x.

Dot Net Framework 1.1 contains version 4.0.1371.1 and it is packaged in _1275__VC_System_PSAPIforNT4_RTL_x86____.msm file - but it is not installed on Windows 98.

This DLL is not part of Windows 98 SE and I'm not sure if it is used on Windows 98 (SE) at all.

Petr

Edited December 13, 200520 yr by Petr

I have psapi.dll 5.0.1849.1 in my Diskeeper Lite directory and I was not sure it was used by Diskeeper on my WinME system (I thought it was only for NT systems because of all those missing functions in NTDLL.DLL) so I removed it and tried to run Diskeeper. It bloked at 60%. I then simply added back psapi.dll in the directory and defrag resumed and completed.

Psapi is not part of WinME either.

Edited December 13, 200520 yr by eidenk

This DLL is not part of Windows 98 SE and I'm not sure if it is used on Windows 98 (SE) at all.

Hmm, thanks Petr. I have since read a few times here and there the same thought as yours. It was suggested that toolhelp.dll is the nearest equivalent in Windows 9x.

However, I have also read about scenarios where individual programs fail to run in Windows 9x, complaining about the absence of psapi.dll, but then start to work when psapi.dll is installed. Thanks eidenk for your own example of this.

From what I can tell, the truth seems a bit more complicated than any statement about psapi.dll having no purpose in 9x systems. It does seem to have a purpose in the directories of some 9x programs. However, I don't know if this also means that psapi.dll is at all useful in the %windir%\system\ directory.

Edited December 14, 200520 yr by bristols

Hmm, thanks Petr. I have since read a few times here and there the same thought as yours. It was suggested that toolhelp.dll is the nearest equivalent in Windows 9x.

However, I have also read about scenarios where individual programs fail to run in Windows 9x, complaining about the absence of psapi.dll, but then start to work when psapi.dll is installed. Thanks eidenk for your own example of this.

From what I can tell, the truth seems a bit more complicated than any statement about psapi.dll having no purpose in 9x systems. It does seem to have a purpose in the directories of some 9x programs. However, I don't know if this also means that psapi.dll is at all useful in the %windir%\system\ directory.

probably not. you can safely delete the psapi.dll file from the windows\system folder as I dont have it on my ME machine. if you are using a program that depends on the psapi.dll file, better to place it in the program's folder than in the windows\system folder.

Windows XP SP2 contains even newer version 5.1.2600.2180 (xpsp_sp2_rtm.040803-2158) and it seems to have the same dependencies - and the same missing functions in it.

I would assume they all do. Windows XP SP3 reads the same.