I updated Java and CS5.5 won't work on my Mac High Sierra 10.13.4.....

Jeff,

Yes, I use Webroot.

Jeff,
I downloaded this and it didn't start Photoshop.  I'm getting this message now from Mac:

Exception Type:        EXC_CRASH (SIGABRT)

Exception Codes:       0x0000000000000000, 0x0000000000000000

Exception Note:        EXC_CORPSE_NOTIFY

Termination Reason:    DYLD, [0x1] Library missing

Application Specific Information:

dyld: launch, loading dependent libraries

Dyld Error Message:

  Library not loaded: @executable_path/../Frameworks/ahclient.framework/Versions/A/ahclient

  Referenced from: /Applications/Adobe Photoshop CS5.1/Adobe Photoshop CS5.1.app/Contents/MacOS/Adobe Photoshop CS5.1

  Reason: image not found

Thanks for the reply. 

Jeff thank you for the response.  When I originally tried to open a file I got the message that I had to install Java SE 6.  I followed the link, but once it was installed it wouldn't start.  I cannot go into Photoshop'a menu.  I now get a Mac message that says in the paragraph:

Dyld Error Message:

  Library not loaded: @executable_path/../Frameworks/ahclient.framework/Versions/A/ahclient

  Referenced from: /Applications/Adobe Photoshop CS5.1/Adobe Photoshop CS5.1.app/Contents/MacOS/Adobe Photoshop CS5.1

  Reason: image not found

Any help would be appreciated and thank you.

If your getting the Java required message to open photoshop cs5.1, then you need the Java SE 6 from apple.

Download Java for OS X 2017-001

If it's something else not working, then you'll have to be more specific.

I believe on a Mac Adobe may use some system Java installing Photoshop.  Once Photoshop  is installed Photoshop Scripts written in Javascript are process via Photoshop's  Plug-in.  Look at your  Photoshop menu Help>System Info.  In there make sure it is loading. ie you should see something like this listed:   ScriptingSupport version xxx.xx - from the file “ScriptingSupport.8li”