Cisco show interfaces at "input errors" counters is high (and some interface resets)

Hi all, does anyone knows what should cause the "input errors" increasing?

We are having periodic random line protocol is down in our serial interface. This interface is Multilink PPP. Does this counters below indicated config problem? (i.e: keepalive 3 set), or hardware problem (bad interface WIC) or line telco problem (input errors & CRC & interface resets)?

Please keep eyes on the show interface result below. I think this should be interesting to troubleshoot. It seems easy but not that easy since we're unable to decide yet what's the root of the problem so far. Hardware? Config? or Line telco?

Any thought? Thanks :)

Serial1/0 is up, line protocol is up
  Hardware is DSCC4 Serial
  MTU 1500 bytes, BW 1984 Kbit, DLY 20000 usec,
     reliability 255/255, txload 188/255, rxload 73/255
  Encapsulation PPP, LCP Open, multilink Open, loopback not set
  Keepalive set (3 sec)
  Restart-Delay is 0 secs
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters 6d16h
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: weighted fair  [suspended, using FIFO]
  FIFO output queue 0/40, 0 drops
  5 minute input rate 568000 bits/sec, 255 packets/sec
  5 minute output rate 1468000 bits/sec, 397 packets/sec
     83554344 packets input, 3151372672 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     2224 input errors, 353 CRC, 1837 frame, 34 overrun, 0 ignored, 0 abort
     114945829 packets output, 1039761406 bytes, 0 underruns
     0 output errors, 0 collisions, 9 interface resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up

Serial0/3 is up, line protocol is up
  Hardware is DSCC4 Serial
  MTU 1500 bytes, BW 1024 Kbit, DLY 20000 usec,
     reliability 255/255, txload 104/255, rxload 15/255
  Encapsulation PPP, LCP Open, multilink Open, loopback not set
  Keepalive set (3 sec)
  Restart-Delay is 0 secs
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters 1d21h
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: weighted fair  [suspended, using FIFO]
  FIFO output queue 0/40, 0 drops
  5 minute input rate 64000 bits/sec, 90 packets/sec
  5 minute output rate 420000 bits/sec, 135 packets/sec
     8378821 packets input, 1496099647 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
     72 input errors, 4 CRC, 38 frame, 30 overrun, 0 ignored, 0 abort
     12296726 packets output, 1246799609 bytes, 0 underruns
     0 output errors, 0 collisions, 461 interface resets
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up