I don't see any reason why not. RAW looks fine, RAI doesn't send up any red flags, either. Unless I'm missing something.
You started moving, but were interrupted before you left the 1st square. I believe you should still have all your actions left. So standing up takes a move, so you should have a standard left, and since you didn't move any distance yet, you should be able to 5' step. If it has taken an AOO for movement already so it doesn't get another one for movement, even if it has Combat Reflexes.
What's the difference between a successful move and a failed one? If you fail to move, you didn't move.
This does seem like a corner case, I'm not sure where I'd land.
I disagree with Valandil Ancalime about the action economy here though - if you took a move action that was ingerrupted you've still used your move action. Since you used a move action to move it does seem reasonable that you wouldn't get your 5-foot-step. If - like Valandil Ancalime - you disagree with the basic premise that you've used your move action then it does seem reasonable that you'd disagree with thos line of reasoning.
Personally I think you'd lose your move action but you'd still be allowed a 5-foot-step (because of the way the rules on 5-foot-steps are worded).
You started moving, but were interrupted before you left the 1st square. I believe you should still have all your actions left. So standing up takes a move, so you should have a standard left, and since you didn't move any distance yet, you should be able to 5' step. If it has taken an AOO for movement already so it doesn't get another one for movement, even if it has Combat Reflexes.
So if I get tripped I can move action to stand up, and standard action to still move away? No. The penatly for getting tripped is losing your move action that you started - the fact you didn't get much use out of it doesn't mean you get it back.
As to the OPs question, no. Once you've used a move action to move you can no longer take a 5' step.
The simplest move action is moving your speed. If you take this kind of move action during your turn, you can’t also take a 5-foot step.
Note, that while still prone, you could continue your movement action to crawl 5'. But as soon as you want to start doing something else that isn't movement, your move action is over, and your standard action starts.
You started moving, but were interrupted before you left the 1st square.I believe you should still have all your actions left. So standing up takes a move, so you should have a standard left, and since you didn't move any distance yet, you should be able to 5' step. If it has taken an AOO for movement already so it doesn't get another one for movement, even if it has Combat Reflexes.
I was thinking of a Readied Action, they interrupt the trigger before it happens.
You started moving, but were interrupted before you left the 1st square.I was thinking of a Readied Action, they interrupt the trigger before it happens.I believe you should still have all your actions left. So standing up takes a move, so you should have a standard left, and since you didn't move any distance yet, you should be able to 5' step. If it has taken an AOO for movement already so it doesn't get another one for movement, even if it has Combat Reflexes.
Just to clarify, you wouldn't get your move action back if it were a readied action either. The readied action happens just before the triggering action as fsr as initiative goes, but the triggering action still happens.
If you cast a spell and that triggers someones readied attack you don't get your sstandard action back, you've already committed to the action so it's lost (or in the case of the spell you make a concentration check etc etc)
Well this particular case works because you're making a mpve action to move, then you're interrupted and tripped, but your mpve action to move continues, it just happens slower (5 feet instead of ~30). Of course this only works if you're tripped from your initial square. If you go to move 30 feet and then you're tripped after the first 10 feet you can't continue your move action while prone, because you only have 2/3 of your move action left, and while prone you can only move 5 feet (so I guess you can move 3 feet, but that has no mechanical effect).
Yes you can continue to attack from Prone, but there are penalties. If you're using a bow to attack you wouldn't be able to continue firing while prone, but you could drop your bow and use unarmed strikes or quick-draw another weapin if you have one. If you're using a melee weapon you could simply continue your full attack action, though you'd take a -4 penalty to your attack rolls.
The main disadvantage of being prone is mobility.
You started moving, but were interrupted before you left the 1st square. I believe you should still have all your actions left. So standing up takes a move, so you should have a standard left, and since you didn't move any distance yet, you should be able to 5' step. If it has taken an AOO for movement already so it doesn't get another one for movement, even if it has Combat Reflexes.
You do not have all of your actions left. You have used whichever action you used that provoked the AOO.