private.php error

[diggity1]

when accessing the inbox, the PMs display but everyone gets this message across the top of the page

Parse error: syntax error, unexpected $end in private.php(2021) : eval()'d code on line 2

i disabled all plug ins under settings plugin/hooks and the message goes away.
i disabled each plug in one by one to see which was the problem and the message doesn't go away.
all i have installed is skimlinks, vboptimize lite and vbookie
all template files are original with the exception of forumdisplay which we have the browsing users at the top. thats about it.

i just upgraded to 4.18 but this has been happening ever since i moved from 3.5 to v4

Any help with this nuisance would be appreciated.