My Macbook Pro charging issue

My Macbook Pro when closed charges normally with the charger. When I am working and it is open the Power charger fluctuates and does not give a consistent charge. I thought it might be a software issue based on previous posts from others regarding other macbook pros. However after recent updates, the problem still exists. Please advise!

MAC OSX: 10.6.8

2.4 Ghz Intel Core2 Duo

4GB 2067 MHz DDR3

Battery Information:

Model Information:

Serial Number: 9G02501CDD3NB

Manufacturer: DP

Device name: bq20z451

Pack Lot Code: 0000

PCB Lot Code: 0000

Firmware Version: 0201

Hardware Revision: 0002

Cell Revision: 0164

Charge Information:

Charge remaining (mAh): 441

Fully charged: No

Charging: No

Full charge capacity (mAh): 4898

Health Information:

Cycle count: 399

Condition: Normal

Battery Installed: Yes

Amperage (mA): -700

Voltage (mV): 10918

System Power Settings:

AC Power:

System Sleep Timer (Minutes): 15

Disk Sleep Timer (Minutes): 10

Display Sleep Timer (Minutes): 15

Wake On AC Change: No

Wake On Clamshell Open: Yes

Wake On LAN: Yes

Display Sleep Uses Dim: Yes

Battery Power:

System Sleep Timer (Minutes): 57

Disk Sleep Timer (Minutes): 10

Display Sleep Timer (Minutes): 25

Wake On AC Change: No

Wake On Clamshell Open: Yes

Current Power Source: Yes

Display Sleep Uses Dim: Yes

Reduce Brightness: Yes

Hardware Configuration:

UPS Installed: No

AC Charger Information:

Connected: No

Charging: No