[ESS] options(error=recover) produces ESS freeze

[Peter Meilstrup]

I keep reproducing a very simple recipe for making ESS and the entire  
Emacs process freeze:

1. set options(error=recover)
2. Move to a buffer where there is a group of statements, one of which  
will produce an error. For example:

options(error=recover)
library(datasets)
avg <- by(warpbreaks, list(warpbreaks$wool, warpbreaks$tnsion),  
function(x)mean(x$breaks)))
#previous line generates error due to typo
print(avg)

3. use C-p or C-r etc. to evaluate the paragraph.
4. RESULT: emacs becomes completely unresponsive.

This makes ESS darn near unusable for me. This can't be normal, can it?

I'm using ESS 5.5 with R 2.10.0 on both emacs 22.1.1 (OS X built in)  
and Aquamacs (22.3.1).

Can anyone shed light?

Peter