archive log prob.

Hi All,
I have this problem ,
while trying to insert a record using sqlplus it just gets hanged .When i tried to look into trace it says

"

Thread 1 cannot allocate new log, sequence 5 All online logs needed archiving
  Current log# 3 seq# 4 mem# 0: C:\ORACLE\ORADATA\AJAY\REDO01.LOG
"

I got a message in between saying oracle is not able to archive log file. I have checked the disk space , looks okay .

Can anyone help me why is this happening . Received on Wed Jan 03 2001 - 12:26:51 CST