If you also need or want to start the patcher without arc, you can start the patcher like this:
1. create a shortcut to your patcher with this target:
"C:\.....\Perfect World Entertainment\Perfect World International\patcher\patcher.exe" arc:1
OR
2. someone in pwi forums reported this:
"I just used the workaround of deleting the Arc lines (174-181) from the stringtab document in the patcher folder and mine updated normally by using elementclient."
OR
3. also to avoid starting arc you can just delete the arcsdk.dll in your launcher folder
OR
4. and last but not least you can disable the autostart of arc or the installation request if you patch the patcher.exe with ollydbg
get ollydbg and change this line at 0x403828 to JMP 004038B4 instead of the original JE 004038B4 then rightclick on the window you made the changes in, choose -> copy to executable -> all modifications. then a window will pop up. close it and olly will ask if you want to save the file.. just save it as patcher2.exe next to the original patcher.exe and start the patcher from now on with patcher2.exe if you want to avoid arc.
this will disable (jump over) the check for arc in the programs binary code itself... if they update the patcher the adresses might change but the pattern should remain the same
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any method should work fine, but the last one will probably survive longer if they fix the other methods
taken from this thread:
spread the word and avoid arc!