Leg pump?

Murf,
Sounds like you are experiencing anterior compartment syndrome (ACS). Shin splints, although painful, generally feel better as you exercise and seldom is there the loss of active dorsi flexion (raising foot/toes towards ceiling). ACS is caused my increased pressure in "compartment" in the front of the lower leg secondary to swelling. The anterior compartment is limited in size and as you exercise increased blood flow to a working muscle causes hypertrophy and subsequent pressure increase. Basically this increase in pressure causes decreased blood flow to the muscle and nerve compression which can be painful and cause the temporary paralysis you are describing. The cardinal sign of ACS is "foot slapping" when you walk or run you will hear your foot slap the ground after heel strike since the muscle that controls lowering it is compromised.

Causes of this problem can be from injury or from overuse among others. Sounds like you have a chronic problem. Treatment is generally based on the severity of the problem. Severe forms can potentially lead to permanent
problems. I would suggest you see a sports medicine doc in your area. They see this problem quite frequently. Conservative treatment would involve, anti-inflammatory med, gait analysis to investigate biomechanics (possible foot orthotics), icing following exercise with ice cups (no wrapping), exercise and massage. Surgery is not uncommon for chronic ACS, a procedure called a fasciotomy is done to relieve pressure and create more space in the compartment when the symptoms become limiting.

You might want to try a bike (stationary or other) as it involves little muscle activity of the anterior lower leg. Ibuprofen before you exercise and icing with ice cup afterwards. If you walk avoid hills, especially down as it requires more muscle activity of the anterior lower leg, a treadmill at .05% would be better than the road. Do not push through symptoms as they will get worse.
Go to a good running store, not Foot Locker or large chain, and get a good pair of shoes that are compatible with your weight and foot mechanics. Off the shelf inserts in your shoes may also help because the more your foot "collapses" the more the anterior shin muscle needs to work. This is a treatable problem but do not ignore it, go see a sport-med doc.

Good Luck, Keith