No Brenda, that would not be the correct translation. If something was σταματημένο it would more likely be a case of something being stationary. Further context will be necessary to comment on the rest of your question.
Note: It's quite important to remember that, while "to stop" and σταματώ have one meaning (stop), they can be transitive or intransitive.
I stop (no object) or I stop something (object). I will include the object for the transitive verb.
Let's see if we can clear this up (including points made already):
Say you talk to someone on your phone and say
1) "I have stopped for a while" = "'Εχω σταματήσει" (pref) or "Είμαι σταματημένη" NEVER "'Εχω σταματημένο/η"
2) "There's been an accident and I have been stopped (as in the car's not moving)" = " Έχω σταματήσει" or "Είμαι σταματημένη" NEVER "Έχω σταματημένο/η"
3) "The police has stopped me" = "Με έχουν σταματήσει", "είμαι σταματημένη". There's also "έχω σταματηθεί" but this from is not widely used (for this verb alone).
The whys and hows of these three.
The verb in the active voice in perf is "έχω σταματήσει". Meaningwise it only conveys that you have stopped. While it may be involuntary as in the second example, well, we're not always that accurate when we speak are we.
There's also the type "έχω σταματημένο". This one needs some explaining. Σταματημένος is, as shawnee said, the participle of the passive pr perf. What is it doing in the active voice you may ask.
Well, in older grammars it's not even considered part of the pr perfect (act). Since, however it translates as "I have something stopped" (see shawnee's post #6) you can say it has an active meaning.
In other words, up to now we have
"I have stopped" (intr) = 'Εχω σταματήσει
"I have stopped something"(tr) = 'Εχω σταματήσει κάτι or "Έχω κάτι σταματημένο"
Wait! You may say. 2 ways for the transitive? Yep. The basically mean the say thing and can be used interchangeably but there's difference in meaning
"έχω σταματήσει το ασανσέρ και φορτώνω τα ψώνια" = I have stopped the elevator temporarily, for an instance as it were.
"έχω σταματημένο το ασανσέρ για να το επισκευάσουν οι τεχνίτες" = Ι have stopped and am keeping it stopped.
Of course the duration maybe of importance only in one's mind
"Why are you yelling at me? I have stopped the elevator only for 5 minutes to load it up"
"Where the hell are you! I have stopped the elevator for 5 whole minutes waiting for you!"
Now to example number 3
Note that passive voice in modern Greek covers some of the intransitive verbs' meanings, the ones that in English take a reflexive noun (I untied myself, I washed myself etc).
So we have
a) έχω σταματηθεί = Someone else stopped me. As I said this form is not widely used for this verb but I'm mentioning it just because it is for other verbs
b) είμαι σταματημένη = Literally I am stopped (therefore I have stopped)
The third option ("Με έχουν σταματήσει") is active (They have stopped me) but you see why I included it I hope (this post is long enough as it is)