How to trace PHP errors
Notice: Trying to get property of non-object in eval() (line 3 of /home/sltruweb/public_html/modules/php/php.module(74) : eval()'d code).


If we break this down, we get:


Severity: Notice. From PHP's perspective, not a big deal.
Actual problem: "Trying to get property of non-object". You have something like this: $foo->bar, where $foo is not an object, and as such, ->bar does not apply
line 3 of /home/sltruweb/public_html/modules/php/php.module, where the problem is happening.
eval()'d code: Your actual problem.


PHP Supports something called eval(). Eval() has some, but very few legitimate uses, and in most cases should be spelled "Evil", instead. Unfortunately, it's used liberally in the Drupal world because there's a module in Core that makes it easy to use. To support my argument, "Don't use it", I quote from PHP's own documentation:


  The eval() language construct is very dangerous


Now somewhere in your site, you have an eval(). And that's one of the many issues with it, based upon your error message, I can't tell you any thing more meaningful than that. To track this down better, you need to update your question with a stacktrace. This however, is not necessarily easy to produce, and you may need the help of a skilled developer.