No matter what I do, whenever I bring up a third party arp plugin to run beside a VSTi in Ableton Live 8.2.1, the VSTi disappears, and the same happens when I bring the VSTi back - the arp disappears.

This has happened to me with three free arp plugins: Kirnu, KlangManipulation's MIQU, and WOK's SimpArp. Since my only experience with arps has been with Live's very own arp (no probs there), and the documentation on those free plugins on this matter is vague at best, the feeling I get is that I'm having a noob moment here. Can anyone tell me what I'm doing wrong?

Bump...

That's because your trying to put the arp plugin and vst on the same track.
Just load the vst, then grab and drag the arp vst to "an empty" space to the right of that track.
It will then create a new track automatically.
Then you have to set your i/o correctly.
Like midi to "arp vst" or midi from "vst" from the drop down i/o menu there.
You'll figure it out.
Might want to check your Live preferences also. Maybe you have to check your midi routing setup too.

The freeware arps your talking about, do not work like Lives own.
The Live arp will go into the same track, like an effect, but those other arps do not. They go onto a separate track, then set your i/o to get sound through midi settings.

Load the arp plug onto it's own track, then send the midi from that track to the instrument (which is also on it's own track) using Live's I/O options.

Just spent Sunday afternoon messing around with the arps I mentioned together with my newly acquired Synapse Dune, and I wanted to thank you for your help!

It was intriguing to see what these three freeware arps offered - KlangManipulation's MIQU was the most flexible of the bunch, although admittedly I'm still struggling to get used to its slightly arcane layout (where's the latch?). Kirnu is pretty good, but it needs deeper investigation, and WOK's SimpArp is, like the title says, a simple arpeggiator, but I particularly love the tightness of its gate...out of the three, it's the only one that gives you that "will it/won't it break down?" feel out of the sounds you throw at it. I can't really put my finger on it, or explain better what that term illustrates, but it seemed to lend an analogue sheen to the Dune...pity that it's not as deep as the MIQU.

Round two continues tonight...this time with Monomo's Emerge soundset!
In the meantime, feel free to chip in about your favourite arpeggiators and step sequencers, freeware or payware - looking forward to hear from you lot!

I take it you figured the arp thing out then.
My suggestion, of which I use...is Thesys by SugarBytes.
It's not an arp, but a sequencer which can easily do arp patterns, then you can just transpose easily if needed.
The demo is great, and unrestricted for (if I remember correctly) 15 days.
It nails the arp patterns, and simply does much more...like the scales and chords, and automation, midi export. Gates, etc.
Check it out here.
http://www.sugar-bytes.de/content/products/Thesys/index.php
You set it up similar to the arps you used, but the i/o settings may be a bit different.

Thanks for the tip Michael...I'll be trying that out too.
However, I think I found what I was really looking for - Defective Records Cyclic step sequencer.

http://defectiverecords.com/cyclic/index.html

EDIT: Just found out it's a standalone, not VST...DAMN!
I wonder if there are any sequencers of that ilk...the closest i've seen is the Algo Music Atomic.

Tried out Kirnu tonight...it would have been perfect if it had the facility to tie notes for that 303-style glide. If it was payware, that would be unforgivable. What a pity!