title: Error creating R data.table with date-time POSIXlt
body: <p>Problem creating data.table with date-time column:</p>
  
  <pre><code>&gt; mdt &lt;- data.table(id=1:3, d=strptime(c("06:02:36", "06:02:48", "07:03:12"), "%H:%M:%S"))
  &gt; class(mdt)
  [1] "data.table" "data.frame"
  &gt; print(mdt)
  Error in `rownames&lt;-`(`*tmp*`, value = paste(format(rn, right = TRUE),  : 
    length of 'dimnames' [1] not equal to array extent
  
  Enter a frame number, or 0 to exit   
  
  1: print(list(id = 1:3, d = list(sec = c(36, 48, 12), min = c(2, 2, 3), hour = c(6, 6, 7), mday = c(31,
  2: print.data.table(list(id = 1:3, d = list(sec = c(36, 48, 12), min = c(2, 2, 3), hour = c(6, 6, 7), m
  3: `rownames&lt;-`(`*tmp*`, value = paste(format(rn, right = TRUE), ":", sep = ""))
  </code></pre>
  
  <p>Create as data.frame and convert to data.table works!</p>
  
  <pre><code>&gt; mdf &lt;- data.frame(id=1:3, d=strptime(c("06:02:36", "06:02:48", "07:03:12"), "%H:%M:%S"))
  &gt; print(mdf)
    id                   d
  1  1 2014-01-31 06:02:36
  2  2 2014-01-31 06:02:48
  3  3 2014-01-31 07:03:12
  &gt; mdt &lt;- as.data.table(mdf)
  &gt; print(mdt)
     id                   d
  1:  1 2014-01-31 06:02:36
  2:  2 2014-01-31 06:02:48
  3:  3 2014-01-31 07:03:12
  &gt; class(mdt)
  [1] "data.table" "data.frame"
  </code></pre>
  
  <p>Am I missing anything or is it bug?  If a bug, where do I report it?</p>
  
  <p>Note I use R version 3.0.0 and I see some warnings re. packages built with version 3.0.2.  Can it be the problem?  Should I upgrade R itself?  Everything else I do seems to be working though.</p>