DB choking on comma delim floats (aka Polyline data)

Not sure where start with this, here is a little background: I am
working on a GMap engine, and the CMS core it builds on uses ADOdb to
abstract the database connections.

That said on with some detail.

In testing some polyline editing tools I notice mysql gagging on a
polyline string of data, like this:
-73.65234375,40.58058466412761,-75.322265625,41.261291493919884,-73.89404296875,41.902277040963696,-73.65234375,40.58058466412761
I get this error when I try to enter that data through a phpMyAdmin
interface:
"The server encountered an internal error or misconfiguration and was
unable to complete your request."

So, the problem is not my engine per se, but seems to be something
about the string or how I have set up the database.

Here is the schema for my polyline table, the polyline data gets stored
in points_data:
'bit_gmaps_polylines' => "
polyline_id I4 AUTO PRIMARY,
user_id I4 NOTNULL,
modifier_user_id I4 NOTNULL,
created I8 NOTNULL,
last_modified I8 NOTNULL,
version I4 NOTNULL,
name C(255),
type I4 DEFAULT 0,
points_data X,
border_text X,
zindex I8
",

Since the core CMS supports a variety of database types I am looking
for some insight from those with deep db knowledge on how to solve
this. (which is why I have not yet gone the route of something like
this: http://www.map-server.com/googlemaps/tutorial_polylines.html)

Thanks!